Here's my input:

Since you say:

First consider wow is not my only purpose but the main one.
I will go against what others have said and say that there's no way I would by a new m/b these days that isn't SLI capable. While wow doesn't really need SLI, and multi-monitors flat out don't support it, most games will benefit greatly from having another video card. Even if you don't get one now, having the option in the future is well worth a few extra dollars on the m/b, imo.

I don't agree that Vista is better performance. It's pretty close these days, and I would probably consider vista just for forward thinking, but I still think XP is faster overall. If you're looking for straight out performance, I think XP still takes it (CAVEAT: I don't know about dual-view in vista compared to XP. XP dual-view isn't to swift, and I've heard that vista is better, but I have no personal emperical evidence to support that supposition).

If you get any 32-bit OS, there is no reason to get more then 4G of RAM.