Simplified buying guide ...

If you never play 3D games, any cheapest new video card that fits your computer is fine. An existing integrated video card (in almost every new business PC) on the motherboard is good too. Forget about the high performance video cards altogether.

3D gamers, check out the following performance charts
http://www.tomshardware.com/site/vgacharts/index.html
then pick one card with overall good performance and do a price search on the Internet. Pick a cheaper one if it's over the budget :) More and more video card manufacturers only use nVidia, ATI chips or both and provide lifetime warranty. It's not like buying US cars or Jap cars :) they're more or less the same.

Make sure the card has:
- right bus interface (PCI, AGP, PCI Express)
- all monitor/TV interfaces you need (VGA, DVI, S-Video)
and make sure your PC is:
- roomy enough to fit some large card
- capable of deliver very large current. A 100W power surge is not uncommon from idle to intense 3D games.

Existing nVidia or ATI users who want to switch brand may need to use the free DriverCleaner Pro (http://www.drivercleaner.net/) after uninstalling drivers to make sure the system is clean for the new card.