I have to buy a gfx card and i dont know which one
its either this one :
XFX GeForce 8800 GT 512MB XXX ALPHA DOG 8800GT
price is 239.99 +shipping 20.00
or this one:
XFX GeForce Nvidia 9600 GT 512MB
169.99 +shipping 10.00
Which one is better for the performance and value?
At least 6? I would not count on that for ANY card. By the time that rolls around, even the highest end card would probably at the very low end at best. You are better to save your money, but get a decent card, and then add memory, swap to another card later. But 6 years is asking a lot.
Btw, SLI is ok, getting better, but in some cases you might be better with 1 high end card as opposed to 2 lower end cards. However once you get toward the high end like 8800gt or above, that may be changing.
DX10.1 is a minor revision to the current DX10, and should not be viewed as an 'advantage' to buying a lesser-powered ATi solution. Furthermore, no games currently support it and I've yet to hear any rumors of games coming out soon that will utilize it.
Edit: Getting a 8800GT or 8800GTS512 would be a good 6-year solution if you add a second card in 2-3 years time. Think about how weak a nVidia Ti 4600 or ATi 9100/8500AIW is. That was high-end 6 years ago today (among the solutions from 3Dfx). It was right at the time AGP 8x was immerging (and all three solutions mentioned were running on AGP 4x buses)! Now has anyone seen benchmarks of Crysis or WIC on them? Didn't think so. Since PCIe is ~1/2 way through it's lifetime we'll almost definitely see a change in interface if not more in 6 years (Larrabee and integrated graphics on CPU anyone?).
Btw, why the low resolution? Just thinking if you want your card to last for 6 years, buy the best you can afford, that way it should last you as long as possible, the 8800 gt might be your best choice if you want to pay extra.
How about this? Little more than your 9600gt, but think it would be better. Looks like a factory overclocked 8800gt, right around 200 before shipping.
You will probably want to upgrade your card long before the 6 year mark. I'm running my X800XL I bought nearly 3 years ago now, and it's getting to the point where it isn't cutting it any more. I can play CoD4 @ 1200x768, but that is as far as I can go that is playable. Even at that resolution, I only average a hair over 30fps.
Cards are dropping in price pretty quickly, but I don't really see them getting a lot cheaper for a while yet. I think that now would be a good time to buy. If you keep your eyes peeled, I've seen a 8800GT go for under $150. I'm going to get a 8800GTS (G92), but I'm waiting for a new motherboard by nVidia to be dropped, hopefully this month (the MCP7A).