This is what I'm running now....playing wow and just downloaded the crysis 2 demo and getting very playable fps.
Phenom II X2 555 unlocked triple core @ 3.76ghz
Cooler master Hyper 212+ CPU cooler
6GB DDR3 Ram 1333
(3) 21.5" Asus 1920x1080 monitors in EYEFINITY
My rig started off as a budget rig and recently added the GPU, PSU (upgraded from antec 380), monitors for eyefinity
This is more of a things to think about.....
If you play wow you will want to go with a more powerful video card if you plan on playing at ultra settings. From what I've read WOW does not support crossfire so by getting a 5770 (good card for the price) when/if you decide to crossfire you may see little if any difference from a single card solution. The 6950 gives me playable frame rates even in eyefinity 5760x1080, but is brought to its knees in large battles with tons of AoE. I want to crossfire but not sure its' worth the money for wow as it's been a complete mixed bag on success stories.
I was also looking at the Asrock MB aznshinobi recommended, which is a very good value for what you get. If you bought 5770's the 8x8 bandwith would be fine but if you start with one 6950 with plans for another you will want a board with 16x16 or plan on losing 5-10% performance, but more importantly the cards are big and run warmer so you will want a MB that has decent separation between PCI-e slots for good air flow.
My PSU only has (2) 6+2 pin connectors so while it will power two 6950's in crossfire I will have to buy 4pin molex to 6-pin adapter's to make it work, which it will but would rather have (4) 6+2 pin.
I like Aznshinobi's build it's solid....
To recap...Yoiu may want a power supply that will handle more/bigger upgrades they're gonna happen (you will save yourself money in the longrun)
WOW does not show benifits from Crossfire (yet), from everything i've read A single powerful GPU will handle it much better especially if you raid, bg's etc
If you go with something on par with the 6950 look for a MB with 16x16 PCI-e slots that have good seperation. May even want a board that has 3 or 4 PCI-e
to get that.
At most that build is worth 500$. The chuck of the build would be the chip (200$), the GPU (120$) and the windows. Which would amount to 400$. However I would think that if you did that, you might as well wait for Sandy Bridge. The i5 2400 is cheaper by about 20-30$ and in fact beats the i5 760.