我觉得台湾的源比较正宗,呵呵,个人见解
deb http://cn.archive.Ubuntu.com/ubuntu/ natty multiverse
deb-src http://cn.archive.Ubuntu.com/ubuntu/ natty multiverse
deb http://cn.archive.Ubuntu.com/ubuntu/ natty-updates multiverse
deb-src http://cn.archive.Ubuntu.com/ubuntu/ natty-updates multiverse
deb http://security.Ubuntu.com/ubuntu natty-security main restricted
deb-src http://security.Ubuntu.com/ubuntu natty-security main restricted
deb http://security.Ubuntu.com/ubuntu natty-security universe
deb-src http://security.Ubuntu.com/ubuntu natty-security universe
deb http://security.Ubuntu.com/ubuntu natty-security multiverse
deb-src http://security.Ubuntu.com/ubuntu natty-security multiverse
deb http://archive.canonical.com/Ubuntu natty partner
deb-src http://archive.canonical.com/Ubuntu natty partner
Ubuntu 11.04台湾源
deb http://tw.archive.Ubuntu.com/ubuntu/ natty main universe restricted multiverse
deb-src http://tw.archive.Ubuntu.com/ubuntu/ natty main universe restricted multiverse
deb http://tw.archive.Ubuntu.com/ubuntu/ natty-security universe main multiverse restricted
deb-src http://tw.archive.Ubuntu.com/ubuntu/ natty-security universe main multiverse restricted
deb http://tw.archive.Ubuntu.com/ubuntu/ natty-updates universe main multiverse restricted
deb-src http://tw.archive.Ubuntu.com/ubuntu/ natty-updates universe main multiverse restricted
SRT Sources
deb http://Ubuntu.srt.cn/ubuntu/ natty main restricted universe multiverse
deb http://Ubuntu.srt.cn/ubuntu/ natty-security main restricted universe multiverse
deb http://Ubuntu.srt.cn/ubuntu/ natty-updates main restricted universe multiverse
deb http://Ubuntu.srt.cn/ubuntu/ natty-proposed main restricted universe multiverse
deb http://Ubuntu.srt.cn/ubuntu/ natty-backports main restricted universe multiverse
deb-src http://Ubuntu.srt.cn/ubuntu/ natty main restricted universe multiverse
deb-src http://Ubuntu.srt.cn/ubuntu/ natty-security main restricted universe multiverse
deb-src http://Ubuntu.srt.cn/ubuntu/ natty-updates main restricted universe multiverse
deb-src http://Ubuntu.srt.cn/ubuntu/ natty-proposed main restricted universe multiverse
deb-src http://Ubuntu.srt.cn/ubuntu/ natty-backports main restricted universe multiverse
Ubuntu 11.04网易源(速度很快)
deb http://mirrors.163.com/Ubuntu/ natty main universe restricted multiverse
deb-src http://mirrors.163.com/Ubuntu/ natty main universe restricted multiverse
deb http://mirrors.163.com/Ubuntu/ natty-security universe main multiverse restricted
deb-src http://mirrors.163.com/Ubuntu/ natty-security universe main multiverse restricted
deb http://mirrors.163.com/Ubuntu/ natty-updates universe main multiverse restricted
deb http://mirrors.163.com/Ubuntu/ natty-proposed universe main multiverse restricted
deb-src http://mirrors.163.com/Ubuntu/ natty-proposed universe main multiverse restricted
deb http://mirrors.163.com/Ubuntu/ natty-backports universe main multiverse restricted
deb-src http://mirrors.163.com/Ubuntu/ natty-backports universe main multiverse restricted
deb-src http://mirrors.163.com/Ubuntu/ natty-updates universe main multiverse restricted
Ubuntu 11.04 上海源 提供 Kernel,Hiweed,ubuntu
deb http://mirror.rootguide.org/Ubuntu/ natty main universe restricted multiverse
deb-src http://mirror.rootguide.org/Ubuntu/ natty main universe restricted multiverse
deb http://mirror.rootguide.org/Ubuntu/ natty-security universe main multiverse restricted
deb-src http://mirror.rootguide.org/Ubuntu/ natty-security universe main multiverse restricted
deb http://mirror.rootguide.org/Ubuntu/ natty-updates universe main multiverse restricted
deb http://mirror.rootguide.org/Ubuntu/ natty-proposed universe main multiverse restricted
deb-src http://mirror.rootguide.org/Ubuntu/ natty-proposed universe main multiverse restricted
deb http://mirror.rootguide.org/Ubuntu/ natty-backports universe main multiverse restricted
deb-src http://mirror.rootguide.org/Ubuntu/ natty-backports universe main multiverse restricted
deb-src http://mirror.rootguide.org/Ubuntu/ natty-updates universe main multiverse restricted
Ubuntu 11.04 搜狐源
deb http://mirrors.shlug.org/Ubuntu/ natty main universe restricted multiverse
deb-src http://mirrors.shlug.org/Ubuntu/ natty main universe restricted multiverse
deb http://mirrors.shlug.org/Ubuntu/ natty-security universe main multiverse restricted
deb-src http://mirrors.shlug.org/Ubuntu/ natty-security universe main multiverse restricted
deb http://mirrors.shlug.org/Ubuntu/ natty-updates universe main multiverse restricted
deb http://mirrors.shlug.org/Ubuntu/ natty-proposed universe main multiverse restricted
deb-src http://mirrors.shlug.org/Ubuntu/ natty-proposed universe main multiverse restricted
deb http://mirrors.shlug.org/Ubuntu/ natty-backports universe main multiverse restricted
deb-src http://mirrors.shlug.org/Ubuntu/ natty-backports universe main multiverse restricted
deb-src http://mirrors.shlug.org/Ubuntu/ natty-updates universe main multiverse restricted
Ubuntu 11.04 骨头源 骨头源是bones7456架设的一个Ubuntu源 ,提供ubuntu,deepin
deb http://Ubuntu.srt.cn/ubuntu/ natty main universe restricted multiverse
deb-src http://Ubuntu.srt.cn/ubuntu/ natty main universe restricted multiverse
deb http://Ubuntu.srt.cn/ubuntu/ natty-security universe main multiverse restricted
deb-src http://Ubuntu.srt.cn/ubuntu/ natty-security universe main multiverse restricted
deb http://Ubuntu.srt.cn/ubuntu/ natty-updates universe main multiverse restricted
deb http://Ubuntu.srt.cn/ubuntu/ natty-proposed universe main multiverse restricted
deb-src http://Ubuntu.srt.cn/ubuntu/ natty-proposed universe main multiverse restricted
deb http://Ubuntu.srt.cn/ubuntu/ natty-backports universe main multiverse restricted
deb-src http://Ubuntu.srt.cn/ubuntu/ natty-backports universe main multiverse restricted
deb-src http://Ubuntu.srt.cn/ubuntu/ natty-updates universe main multiverse restricted
lupaworld 源,提供 ArchLinux,Everest,FreeBSD,Fedora,LFS,Magiclinux,Mandriva,OpenOffice,openSUSE,Puppy,Red Hat,Slitaz,Turbolinux,Ubuntu,中标普华
deb http://mirror.lupaworld.com/Ubuntu/ natty main universe restricted multiverse
deb-src http://mirror.lupaworld.com/Ubuntu/ natty main universe restricted multiverse
deb http://mirror.lupaworld.com/Ubuntu/ natty-security universe main multiverse restricted
deb-src http://mirror.lupaworld.com/Ubuntu/ natty-security universe main multiverse restricted
deb http://mirror.lupaworld.com/Ubuntu/ natty-updates universe main multiverse restricted
deb http://mirror.lupaworld.com/Ubuntu/ natty-proposed universe main multiverse restricted
deb-src http://mirror.lupaworld.com/Ubuntu/ natty-proposed universe main multiverse restricted
deb http://mirror.lupaworld.com/Ubuntu/ natty-backports universe main multiverse restricted
deb-src http://mirror.lupaworld.com/Ubuntu/ natty-backports universe main multiverse restricted
deb-src http://mirror.lupaworld.com/Ubuntu/ natty-updates universe main multiverse restricted
rootguide源,Ubuntu官方上海源,提供 Kernel,Hiweed,ubuntu
deb http://mirror.rootguide.org/Ubuntu/ natty main universe restricted multiverse
deb-src http://mirror.rootguide.org/Ubuntu/ natty main universe restricted multiverse
deb http://mirror.rootguide.org/Ubuntu/ natty-security universe main multiverse restricted
deb-src http://mirror.rootguide.org/Ubuntu/ natty-security universe main multiverse restricted
deb http://mirror.rootguide.org/Ubuntu/ natty-updates universe main multiverse restricted
deb http://mirror.rootguide.org/Ubuntu/ natty-proposed universe main multiverse restricted
deb-src http://mirror.rootguide.org/Ubuntu/ natty-proposed universe main multiverse restricted
deb http://mirror.rootguide.org/Ubuntu/ natty-backports universe main multiverse restricted
deb-src http://mirror.rootguide.org/Ubuntu/ natty-backports universe main multiverse restricted
deb-src http://mirror.rootguide.org/Ubuntu/ natty-updates universe main multiverse restricted
网易开源镜像站,提供FreeBSD,OpenBSD,archlinux,centos,cygwin,debian,Fedora,gentoo,kernel,openSUSE,slackware,Ubuntu
deb http://mirrors.163.com/Ubuntu/ natty main universe restricted multiverse
deb-src http://mirrors.163.com/Ubuntu/ natty main universe restricted multiverse
deb http://mirrors.163.com/Ubuntu/ natty-security universe main multiverse restricted
deb-src http://mirrors.163.com/Ubuntu/ natty-security universe main multiverse restricted
deb http://mirrors.163.com/Ubuntu/ natty-updates universe main multiverse restricted
deb http://mirrors.163.com/Ubuntu/ natty-proposed universe main multiverse restricted
deb-src http://mirrors.163.com/Ubuntu/ natty-proposed universe main multiverse restricted
deb http://mirrors.163.com/Ubuntu/ natty-backports universe main multiverse restricted
deb-src http://mirrors.163.com/Ubuntu/ natty-backports universe main multiverse restricted
deb-src http://mirrors.163.com/Ubuntu/ natty-updates universe main multiverse restricted
搜狐开源镜像站,提供 CPAN,FreeBSD,NetBSD,OpenBSD,apache,archlinux,centos,cygwin,dag,debian,Fedora,gentoo,kernel,lfs,mysql,nginx,openSUSE,PHP,rpmfusion,slackware,Ubuntu
deb http://mirrors.shlug.org/Ubuntu/ natty main universe restricted multiverse
deb-src http://mirrors.shlug.org/Ubuntu/ natty main universe restricted multiverse
deb http://mirrors.shlug.org/Ubuntu/ natty-security universe main multiverse restricted
deb-src http://mirrors.shlug.org/Ubuntu/ natty-security universe main multiverse restricted
deb http://mirrors.shlug.org/Ubuntu/ natty-updates universe main multiverse restricted
deb http://mirrors.shlug.org/Ubuntu/ natty-proposed universe main multiverse restricted
deb-src http://mirrors.shlug.org/Ubuntu/ natty-proposed universe main multiverse restricted
deb http://mirrors.shlug.org/Ubuntu/ natty-backports universe main multiverse restricted
deb-src http://mirrors.shlug.org/Ubuntu/ natty-backports universe main multiverse restricted
deb-src http://mirrors.shlug.org/Ubuntu/ natty-updates universe main multiverse restricted
然后执行: sudo apt-get update sudo update-manager -c -d升级就可以了。