Updating Critical Packages Only

[S Yuval]

I recently bought the Debian 3.0r1 7-CD set and am trying to upgrade some obsolete packages. However, it turns out that if I ask apt to update its package database, most packages I have on the CD-set become obsolete and can no longer be installed conveniently through dselect. Since I cannot afford to spend nights downloading new packages for my entire system, and I purchased the CDs to avoid having to do that, is there any way to tell apt-get to update only the critically important packages like glibc, libstdc++, ncurses, etc. and not the entire system?