Using Nvidia chipset and a Nvidia card are pretty different beasts. Nvidia graphics cards are very well supported and are *the* best card to get for 3D in Linux today. You don't want ATI for 3D, as ATI has yet to release any decent drivers. Sure, there are 3D drivers. They are missing a LOT of GL extensions which makes a huge difference in games such as UT, UT2004, etc. If you have a fast enough CPU you can probably play a simple game like Tuxracer in software mode.
