I us a MSI8600gt 256mb. It cost me $79 at newegg.com. Great card. (mine was open box).
Plus you can play most games at great settings. You maybe able to go lower, but I
recommend this card for everyday use and then some! Also, when searching for a card at
newegg or anywhere else, read the specs and reviews and if your Motherboard has AGP or PCI slots.
Also, check your MB for Nvidia or ATI hardware. Nvidia cards work better on Nvidia boards.