Here's a cool freeware utility for Mac gamers (who love Aspyr especially). When you launch The Aspyr Game Agent (TAGA), it compares your machine's specs to the system requirements of their titles, and displays good matches. If you search for a game that won't run well on your machine (according to the system requirements, at least), TAGA suggests appropriate system upgrades.
It's convenient and fun, though limited to a single manufacturer's catalog. It's also free (and Universal). If you're a hard core Aspyr fan, check this one out.