Linux is a fully functioning, powerful operating system that does not cost you a dime. It has a great community that will help you trouble-shoot and fix problems like driver clashes and hardware support. Unfortunately major software and game developers generally tend to disregard and overlook the OS reducing its attractiveness.
That is about to change as Valve has decided to bring Steam to Linux. Not only that, but they have also made the move to start porting Left 4 Dead 2 to the platform as well. Steam can easily be stated to be the mode of choice for the digital distribution of games. With its presence on Linux, game developers can now more readily take Linux into consideration.