Just go with the best geforce card you can afford.
Agreed, ATI's drivers make the baby Jesus cry. I only know of one thing so far that's caused a blue screen in my limited work with Vista, and it was an ATI driver (NO WAY!!!11). nVidia has by far better driver support, and the hardware on the two lines is generally comparable over a 2-year period. Support makes all the difference in the lifespan and bang-for-the-buck.
For the record, I've been nVidia since they bought out 3DFX (and I was 3DFX before that... VOODOO 2 SLI FOREVER!, 12MB CARDS RULE!)