Hi, I have recently installed Debian Squeeze but I have installed it from the Live DVD and everything works fine. All you have to do after the installation is add the repositories from it's own Live DVD and you are ready to go. Check this site if you want to download the Live..:
http://www.debian.org/CD/live/
If you need a step-by-step on how to install the Nvidia Drivers just let me know I think I might be able to help you with that.
I'll be in touch just in case you want to install it the way I told you.
Good luck and see you soon.