I have a 500GB internal HDD, but I've only used up 250GB. I plan on creating a Boot Camp partition to play games, such as Sims 1-3 (and 4 when it's out) and several Steam games. I would still be doing most of my work on OS X, though. I've had this iMac for 3 years and I share it with my sister. Any thoughts would be appreciated! 