mhh... how bad is it ?
Well, it's not good but try a couple things:
Code:
apt-get -t unstable install debian-keyring
Code:
apt-get -t unstable install install dpkg
then
Code:
apt-get -t unstable install apt
Your computer is a bit resource shy, and depending on what apps you plan on using you might want to check out something like Damnsmalllinux, http://damnsmalllinux.org/

Another distro worth looking at as a LiveCD to HDD is sidux http://sidux.com/