I do have to wonder why the focus on putting it on on 1 box? I can appreciate the techno-phile interest in seeing if it can be done and just how much performance you can squeeze out of a PC.

But from a cost perspective, I'd think it's cheaper to just buy a 2nd box. (e.g. 2x 500watt PSU's are cheaper than 1x 1000watt PSU, 2x 12GB or RAM is cheaper than 1x 24GB of RAM (are there any mobo's that support 24GB of RAM?), 2x GTX 275's are cheaper than 1x GTX 295....)

If you're willing to dedicate ~$150 a month to WoW, maybe price isn't the focus. But I'd think that performance would be better on 2 boxes vs. 1 as well.

I just went through this same sort of cost/benifit comparison when I was setting myself up for 5x boxing. When I looked at the prices of buying a new i7 system vs buying an older Q6600 and off loading 1 or 2 instances to an even older Core 2 Duo system the 2 older sytems were cheaper and offered better performance.