Desktop Graphics Card Comparison Guide
Over at Techarp they have a nice long page with all kinds of video cards, and their specifications. The charts are really nice to look at and easy to use.
They go through things like GPU details, features, and performance for ATI and nVidia video cards.
A very interesting and impressive resource. Sadly, it also reminds me how behind the times I am with my ATI AIW 9600XT.
nVidia cards are on page 2 (I know it can be hard to find, but the link is down at the bottom of the page).