Jenny, I'll send u a copy of my XF86Config-4 and the output from dpkg -l when I get home so you can check if you have the correct X packages installed. (I also have true type fonts set up "which is nice")
What I had to do to get it working from Potato was to manually remove all the X packages, then manually apt-get install the new ones (apt-get dist-upgrade shagged it up). It's a pain, but if you have a working set of packages to crib from, it makes the job a great deal easier.
AFAIK, Woody still has the old X packages included, to aid backwards compatability. So it could be using the old 3.x series... they have *slightly* different package names to the 4.x series... all a bit confusing!
Personally, I used the source from Nvidia's site but that's because I was using a more current kernel than Debian were offering at the time. The drivers really do make a difference. wizzzzz! ;)
Ricardo