Re: which driver for mx4000 on debian ?
Yes you do. It's in Nvidia's site under Linux OS, Duh!
As for installing it, that's another story. It's not as simple as double clicking a EXE file. There is an installation read me on the download site. It's an installation script that works on all linux distributions, so it's not that hard.
I recommend you get a linux book. It helps a lot with command line inputs and configuration. Most of the questions you have may be easily answered in the book. As for what book is good. I have no idea. I use Fedora Core 4
And i bought a book on Fedora Core that got great reader reviews from Amazon.com.
Just follow the instructions on Nvidia's site, and if you have problems refer to a Debian book. That's how you use linux.