Go with the AMD. It's graphics chip will help you out since you'll actually game with it (even if it's WoW).
The lower drive capacity is a pity, but you can upgrade that easily enough. The same can't be said for USB ports (it's only 3 vs 2, but it might just come in handy).
The AMD is a tad smaller and lighter. The difference in screen size and resolution hardly matters.
My only concern is playing HD content. The CoreAVC2 codec is a MUST. You will have no problem playing 720p videos with that, but I can't say for certain whether you'll lag in True HD videos. (My AMD X2 1.6GHz does).