If you're playing some blockbuster game (and The Sims 3), download and install this. Then run it, and let it optimize the game settings for you. As long as your GPU is at least DX10-capable (that'd mean 8-series and newer), and have a semi-recent CPU (Core 2 is pushing it), this'll work its magic.

Better than fiddling manually, and OH MY GOODNESS IS THIS 60 FPS ON SKYRIM WHILE BEING PRETTY to me. (Yes, it works with laptop GPUs, too.)

Just as a note, seeing as this is in Beta, there aren't a whole lot of games that are this is actually compatible with. The full list of compatible games can be found here.