Useful information from Steam users:
http://store.steampowered.com/hwsurvey/
Description from web page:
"Each month, Steam collects data about what kinds of computer hardware our customers are using. The survey is incredibly helpful for us as game developers in that it ensures that we're making good decisions about what kinds of technology investments to make. Making these survey results public also allows people to compare their own current hardware setup to that of the community as a whole."