If they work they are amazing. Especially in the build quality. The only reason I say "If they work" is because when I bought my m17x....It didn't work. Once they sent me a replacement, it worked like a dream. You can see my configuration in my sig.
As to how well they will play games, that all depends on how you configure it, though, the idea behind alienware is to play games. Even the m11 will handle any game just fine at atleast medium settings.