I'm putting the final touches on a new system right now and was debating between buying a pair of 8800GT or GTS cards, or scavenging the 8600GTs out of my old box (I got them cheap, and I had done no research at all; I went to Fry's and asked a frigging salesperson, who told me what he thought I wanted to hear. I consider that purchase to be a case of paying the "idiot tax.") and using them until the "next big thing" came along.
I looked at a 9800GX2 but...ugh. Heat dumping into the case? And if I ever wanted to SLI them the heat problem would be even worse. I'm just not sure this card is a good investment; I want something that'll last me a while, not a gimmick. "Thanks but no thanks," I said.
So I thought I'd wait and see what the 9800GTX was like...and I'm not impressed by this review. I despise an extremely noisy video card, and it sounds like that's exactly what this one is; I'd imagine it's absurd if you SLI them. The performance seems nice, though; I'm just not sure whether or not it's nice enough to justify the irritation factor.
Hopefully the 9900s will be powerful without rattling the windows in your house.