So i'm building a gaming pc. I'm going to be playing World of Warcraft and COD4 mainly. I'm not a Vista fan and will be using XP PRO 64-bit most likely. If everything else in the machine was the same except the video cards would 2 8800 Ultra or a 9800 GX2 give me better performance and fps while gaming? Would appreciate someone more knowledgable with video cards and building pc's to help me out. Also considering getting 1-2 280 GTX's but the cost and power consumption has me leaning away from them.

From the ones you listed, the best for sure is 2x8800ultra. However, these cards are very expensive and not worth their money. If you want to SLI or Crossfire something, get 2xHD4850 or if you already have a SLI mobo, get one HD4870, which is cheaper and MUCH faster than 8800ultra and not that slower than gx2. It even outperforms gx2 in some tests when aa and af is enabled and in SLI-disoptimized games. 4870 is overall 13% slower than 280 if we count GRID, which has some issue with AA and AF on Radeon. And not counting Bioshock, in which 470 outperforms gtx280 by a large margin.
But still a gx2 is a good buy nopw, if you can find a SUB-500$ one.

And the games you're playing. WOW and COD4 don't require such a powerfull card. WOW ran MAXED OUT at 16x10 on my 6800gt's.
And COD4 is not very graphic intensive game. A 9600gt can handle that game well at 16x10 with AA on high.

And 2x8800ultras will consume more enegry than the gtx280 And cost more - look the prices on newegg. I would say go for the gx2 or a hd4870. The only problem is you have a SLI motherboard and getting another gx2 would make no sence to you.

Crossfire 4850 gets you the best out there for the best price.

The AMD cards are the best bang for buck right now. The 8800Ultras are pretty much out of the picture now.

What resolution is your monitor? That will help determine what you will need to play with settings maxed.

As the other posts said, WoW and COD4 are not really that intensive - both proposed solutions are overkill, probably even on a 30" monitor.

Thanks for the help.

I do have a SLI mobo.

Monitor is a 25.5 Samsung with hd and dvi.

A single 4870 will do just fine for WoW and COD4, and anything else that's out right now (assuming you don't play on a 30" monitor). If you're building this PC from scratch then I'd seriously consider getting a Crossfire board instead and going the 4800 route. They're just a better value right now, and depending on how well it scales a 4870+4870X2 system would blow anything but 2xGTX280's out of the water.

Well if 4870x2 scales at 100%, it will blow the gtx280 out of the water for sure
Go for 4870, then chage te board to a crossfire one and then add another 4870 or a 4870x2

Between the 9800GX2 and 8800GTX, I'd definitely choose the 9800GX2. Anyday.

Since it looks like you already have a sli motherboard, get 2 g92 8800gts. At $119.99 after mir, it's serious power on the cheap.
http://fxvideocards.com/ZOTAC-GeFo [...] 16280.html

A single g92 8800gts perform about the same as a 4850, but almost $100 cheaper.
http://www.techpowerup.com/reviews/MSI/HD_4850/10.html
http://www.techpowerup.com/reviews/MSI/HD_4850/15.html
http://www.techpowerup.com/reviews/MSI/HD_4850/17.html

In sli, it outperforms single gtx280, 9800gx2, and far outperforms any single 4850/4870. To cf, you'd need to buy another motherboard.

A stock g92 8800gts perform the same as stock g80 8800gtx, and with oc, matches g80 8800ultra.
http://en.expreview.com/2008/04/02 [...] p/?page=11