Personally, I despise Nvidia based boards. They have issues with intel chipsets. There will be new Nforce boards before february, should be out this month, the Nforce 750i, 780i, and 790i. The 750i is a dual x16 pci-e board that will run two cards at 8x. The 780i will be tri-sli 16x/8x/8x or 16x/16x. The part that is a real slap in the face, these are the same damn chipsets from 650/680, they just added support for PCI-E 2.0 and a BR-04 bridge chip for tri-sli. Damn bastards...GRRR!...If they had a good chipset, I wouldn't mind going a dual card nvidia solution, but if they want to be ignorant and greedy asses, and forbid me from using a intel based board with dual nvidia cards, then they're never getting my money for their shat chipset..But they will get my money for a single high end card ^_^.
lol....ignore my ranting, Hopefully that should help you out. But honestly, WHATEVER board you get, is gonna die at the end of 2008. So no matter what happens...whatever you get that is a intel system, is not gonna have any upgradability except for penryn/core processors.
But the 750i should do a 16x pci-e 2.0 card no problem. That should be good on a budget too without paying too much like a x38/780i board. But do keep in mind, x48 will be released as well, which should tone the prices down on x38. I'm planning to build a rig around February as well, personally, I'm nabbing a x38. If the 9800 nvidia series does happen to break the 2.5 GBit barrier of PCI-E 1.1, I'd rather overpay for x38 then be stuck with a nforce board...
::shakes evil hand of vengeance at nvidia: