You can get a 8800GT for pretty cheap,
http://www.ncix.com/products/index.p...xy%20Techology
I don't think a 7600 can run most of the newer games, And if it can at shitty frame rates :P With a 8800GT It should/will allow you to play new games for atleast a couple years :D Hell, Could probably find some used 8800gt's on ebay for cheap, Seeing has the 1GB just came out...
EDIT: What dimension or w/e is your dell? Try checking google for its mobo, That will tell you if its AGP or PCI-E 1/2