Actually, you can run sc2 and COD MW2 in the MBA as well as in the new MBP...
No, I know. Ive been a SB fan since it was first rumored. the only reason why I didnt buy the 2010 MBP/MBA was only for Sandy Bridge. I knew it was a huge leap. But really, when we are talking about a normal user, why not the MBA over the MBP?
Dont get me wrong, I will buy the MBP 13 by the end of summer if there are no upgrades in the MBA line with Sandy bridge processors. But sometimes people underestimate the MBA. 256SSD just right out kills anything thrown at it, and a 2.13 GHz Core2duo can handle any task.
Unless you are a heavy photoshop user and video maker (which you should be using a 15 instead of a 13), MBA is a great choice for college students, high schoolers, old people, and just normal business people.