下面是ubunut的源列表，详细见http://wiki.ubuntu.org.cn/index.php?title=Qref/Source&variant=zh-cn，
经本人亲测，163和搜狐的好像都不行，我用了LupaWorld，速度还可以。
更新服务器（浙江杭州电信联通双线服务器），包含其他开源镜像 ：
deb http://mirror.lupaworld.com/ubuntu natty main restricted universe multiverse deb http://mirror.lupaworld.com/ubuntu natty-security main restricted universe multiverse deb http://mirror.lupaworld.com/ubuntu natty-updates main restricted universe multiverse deb http://mirror.lupaworld.com/ubuntu natty-backports main restricted universe multiverse deb http://mirror.lupaworld.com/ubuntu natty-proposed main restricted universe multiverse deb-src http://mirror.lupaworld.com/ubuntu natty main restricted universe multiverse deb-src http://mirror.lupaworld.com/ubuntu natty-security main restricted universe multiverse deb-src http://mirror.lupaworld.com/ubuntu natty-updates main restricted universe multiverse deb-src http://mirror.lupaworld.com/ubuntu natty-backports main restricted universe multiverse deb-src http://mirror.lupaworld.com/ubuntu natty-proposed main restricted universe multiverse