Kind of impossible to say. Depends how devs make games in the future.
The X1600 has more raw shader power but the 6800GS has more raw pixel pushing power. Both have strengths & weaknesses.
This is for AGP right? Because in PCI-express the obvious choice is the new 7600 GT. Should be under $200.
But in AGP, hard to say. I don't think you'll be upset with either choice. Neither is the best card, but both are solid. If you're an overclocker the X1600 probably has more headroom to play with. Then again, there is a game or two it performs badly with, like Call of Duty 2. It's more inconsistant than the 6800 GS.
Ditto, what Cleeve said, the GF7600GT will smoke them both and then some for games. And as for portending to the future, just look at the HL2-HDR, BF2, F.E.A.R. and Serious Sam 2 results, all could be considered future-facing games, and the GF7600 just walk alway with it by double digit % gains.
The only exception IMO is for 2D video where ATi's AVIVO is nice. But in this case I'd make an exception to my usual missives about 'magic future drivers' and say that the gaming performance benifit of the GF7600GT is worth the risk of the promised improved PureVideo drivers (and the promise they'll be FREE finally).
Definitely the GF7600GT for PCIe, solid bang for your buck, and in no way 'crippled', which is more than I feel I can say about the other two cards.
the 7600gt is better than a 6800GS which is better than a 1600XT... a the x800gto2 slots in between the 6800gs & 1600XT but its only PS2, not futureproof but raw power is quite good (a 1800gto is better plan these days anyhow...)
Would it be cheaper for me to just buy a new motherboard and a PCI express card?
Can someone find me a cheap motherboard witha PCI express, I really have no idea how to tell if something is good, I need at least 3 RAM slots, PCI express slot, 2 PCI slots, umm yeah I don't really know.
I was going to order a $225 eVGA 6800gs AGP, but if the 7600GT is cheaper than that, then why pay more for less? Can someone help me out?