Good question. Considering SLI doesn't directly double your GPU power, I'm guessing the 295 would win, but that's 2 9800s we're talking about here! Well, I have 2 7950 GT's, and they run games slightly faster than my 2 9500s, I don't know why. I'd put my money on 1 GTX 295 because the 295 has over 223 Gbps of bandwidth where the 9800 only has around 60. If it was 2 9800s vs a GTX 260, it'd be a different story. But then again, the 9800s are known for being slightly flawed. Either way, both sides of the argument are super fast.
Your signature has been erased by a mod because it's too big--- 300k!?