single GPU or SLI??

Just get a high end GPU then upgrade after about 3 years....SLI is just a waist of Money Right now.

Hypothetically speaking if cost was not an issue then you could buy two of the best SLI cards every time a new one comes out.

Practically speaking it would be best just to buy a high end card every year. Why? Because just about every game made can run on maximum settings with the latest Graphics Card. If you always have the latest Graphics Card then other factors will contribute more to your game performance ratings such as CPU speed, HDD speed etc.

As I have said before, 2 Graphics Cards != 2X performance. On most benchmark scales, it's about equal to 1.5X performance.

Summary: If you can already run games on maximum settings on the latest card then you don't need a second graphics card.

Imo is that when your gonna SLi, you must buy like 2 of the best cards on the market, or its a waist of money,

but if you cant afford it, just buy a single GPU. and btw many of the newer games arent that demanding so you dont

really need Sli, but its a plus. 

For what it's worth, each new generation of GPU seems to see bigger and bigger SLi performance improvements.

It seems with each new generation of GPU that nVidia makes, they are ever inching closer to achieving the theoretical "2x the performance" output that such a system would theoretically give you. But of course this difference is much larger if you start with some high-end GPU's to begin with.

One thing that SLi also grants you is the ability to keep your hardware running when you sell a part to try and save up for an upgrade. Example...

Say around launch, I bought a pair of 7900's for SLi. Now a few years later, I find the 8800's drool-worthy. I can sell one of the cards to build up my money and help me get an 8800, while still having the other 7900 to keep my computer working.  Then once that one is sold and I have one 8800, I can then sell the other 7900 and get the second 8800 for SLi.