iluvgillgill :
get the new 8800gts.its future proof for at least 2 year from the speed games are develop these days.
I think you're statement is off, way off. Lets look at it this way, two years ago would have been March of 2006. I think it is possible, that the 'next-to-top-of-the-line' GPU in 2006 was the best GPU in 2005 (or atleast performance wise is).
Accodring to Tom's Charts, the best card in 2005 is 7800GTX (Or the ATI X1900 XTX). There are of course SLI and Crossfire options, but for this conversation, we'll leave them out of it (which doesn't make the scenario any better).
The Best cards in 2005 (which would mimic the 2nd tier card in 2006) only achieves 958/1577 (Nvidia/ATI) at a 1600x1200 resolution. This is closely the current day 2600 XT is readily available for about $75. I wouldn't want to be a gamer in these days with a 2600xt.
On the flipside, the X1900 XTX current day equivalent is an Overclocked 8600 GTS. I realize that there are people gaming on 8600GTS today, but woudl you consider it "current-gen-proof?"
I would recommend that you buy the best card available given your budget (and also look at the cards just outside your current budget--if $50 is the difference between a 2600XT and a 9600GT, you should be aware of the options). Once the performance of the card you buy falls below your expectations (or minimum gaming limits of detail/fps), then develope a new budget and start the process over again.
Using this method, you could probably get away with a $200 GPU purchase every 18-24 months (which does not make the card future proof).