Well this is a matter of preference. One wya to look at it is, how much bang for your buck?
Heres a couple links that will let you see for yourself. The first is a review of all the cards worth mention and what their frame rate capabilities are on certain games.
http://www17.tomshardware.com/graphi...418/index.html
Read (or at least look at) all the pages there to see what cards can do what.
Next is a comparison of the Geforce4 ti boards. These are the new big boys on the block.
http://www17.tomshardware.com/graphi...304/index.html
Quite an informative page. If you really want to learn what the G4 ti boards can do read that thoroughly, in particular the benchmarks section.
http://www17.tomshardware.com/graphi...206/index.html will tell you what the real differences between the G2 G3 and G4 cards are.
God I love this stuff