You can get a 8800GT for pretty cheap, [Only registered and activated users can see links. ]
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
i think that card is a waste of the money with a 4 year old Dell which might actually belong to 5 to 6 years ago .even if it can support it
you must consider a computer as whole not just parts .you cant put an f22 engine on a f5