Quote:

NVIDIA GeForce

...or...

ATI Radeon?



It depends on the platform. Graphic card drivers aren't a trivial piece of software and they have to be written specifically for whatever operating system you use. I use Linux, so Nvidia. Although Intel is becoming more popular. I think I remember seeing somewhere that ATI has better drivers for Macs than nVidia does, so double check that.

Windows, it doesn't probably doesn't matter either way. But, as stated previously, read reviews of the most graphics intensive software you want to use to see if it can make use of some random feature that's on one card but not the other.