If it comes with Windows 7, yes, that's a decent computer for the price (with the same caveats as tecmo).
As for WoW, depends on what resolution you are playing at and what you are doing. It is going to have trouble in raids if you're gaming at 1920x1080 with all settings on Ultra. If you set to high or have a lower resolution or you don't raid, you'll be fine. Dalaran will probably be around 30 fps, but everything else should be better.
Yeah, I was pointing out that the parts you've picked out should do better than 30 fps everywhere else.
I get 30 fps in Dalaran with settings on Ultra with a 5870 and an AMD Phenom II X4 at 1920x1200, 40 fps with shadows turned down. In general, everywhere else is better. Assuming you turn down to high or game at a lower resolution, you should be more than fine.