This is the default "/etc/apt/sources.list" from a newly installed Linux Debian 6.0.5 (Squeeze).
Excluding the cdrom row..


These are all using the Swedish Debian mirror.

deb http://ftp.se.debian.org/debian/ squeeze main
deb-src http://ftp.se.debian.org/debian/ squeeze main

deb http://security.debian.org/ squeeze/updates main contrib
deb-src http://security.debian.org/ squeeze/updates main contrib

# squeeze-updates, previously known as 'volatile'
deb http://ftp.se.debian.org/debian/ squeeze-updates main contrib
deb-src http://ftp.se.debian.org/debian/ squeeze-updates main contrib