You can definitly skip the dual core and save some cash.
The thing about dual core chips is 99% of applications out there won't use the second core. Why? Because a program must be compiled for dual CPU support in order to use them. What applications support 2+ CPUs? Windows XP Pro (just the OS), Oracle Database, 3D Studio Max, Maya, other expensive software that you and I will probably never use
The RAM, I've never seen World of Warcraft use more than 524MB, so 1GB of RAM is really going to be enough. The only program I have ever seen use more than around 500MB is FireFox .. really, my box was responding really slowly, I opened TaskManager, and found FireFox using 1,044,252k; it was probably some memory leak from the dozens of extensions I have.
The Video, well, WoW doesn't have great graphics, I'm running the game at 1600x1200 with the graphic settings totally maxed out. I have dual PCI-E 6600, using SLi.
The LanParty board, EXCELLENT selection, I have two of these boards and have built two other PCs with them, they are wonderful!