Laptops in general, and in a lot of cases Apple laptops specifically, make for absolutely HORRIBLE gaming platforms. Just awful. Small screens, slow response rates on the screens, cramped keyboards, you need some kind of external mouse to make it workable. Then there's the heat issue, which will kill laptops in a hurry, and Apple systems in particular since they're quite a bit thinner than the competition.

If you only plan to play maybe an hour a day or less, then maybe, but I would say you'd be much better off getting a device that is designed from the start for gaming such as the PS3 or Xbox 360. Even those may not quite be set up to handle marathon sessions of 3-4+ hours, but they should be able to handle 2-3 hours without any real issues. Don't think I could say the same of ANY laptop, even laptops specifically designed for gaming, because those things tend to burn themselves out in 6-12 months. It's pretty rare to see an Alienware laptop that is over a year old that hasn't gone in for at least one major repair in that time.

So maybe just hold off a little longer, and buy both the 15" MBP and a PS3/360.