" You're a gamer? Then why the hell do you have a Mac? Get a PC. "
right, that old argument again. sorry, but it doesn't hold any weight. you don't need to own a pc to consider yourself a gamer. i tend to play games on the xbox 360 and the ps3 and my main compuer is a macbook pro. sometimes i boot the windows partition on it to play some steam games, but it is not very convenient.
also, directx is not a must. look at all current and upcoming blizzard titles, opengl looks just as good as directx.