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Some movies on DVD have a calibration guide built in. I've used these on my monitor before and it worked great, but I have no idea what movies include this, and whether you have any of them. Other than that and the resources mentioned in earlier posts, you might want to check this out:
This PCWorld article discusses a number of methods for calibrating your monitor. It mentions that Windows 7 has some built-in calibration tools (one would assume Windows 8 also does). It also cites a web-based calibration tool at a site called DisplayCalibration.com. And if you're up for spending some money, there are many automated calibration tools available such as Spyder 4 Express, which costs $119.