In my opinion, 2600 bucks is a lot of money. And I mean it.
You can buy a desktop and a laptop altogether and I think that's the way to go. Computers don't usually need that much money but if you want, spending about 1600 on a laptop would be enough to get you a Lenovo/Vaio that would last you about 3 to 4 years. If you want, you can always buy a new one because in 3 to 4 years, laptops are usually obsolete.
Spending an extra thousand dollars would probably buy you an extra 3 months before the laptop become obsolete and that really isn't worth it.
Instead, if you want to play games, you might wanna consider buying a desktop in addition to your laptop. A thousand dollars worth desktop is good for playing various kinds of games, and might even play Crysis [One of the most graphic intensive game nowadays] with the low setting.
You just gotta know what to buy, but buying an alienware isn't worth the money. [Except if you are just looking for money to waste]
Edit: Additionally, you might not want to get a mac if you are into gaming because not a lot of games are compatible with the mac operating system.