(Reproduced from: http://www.microsoft.com/windows/windows-7/upgrade-advisor.aspx)
In general, if your PC can run Windows Vista, it can run Windows 7. But if you’re not running Windows Vista, or are just not sure if your system is ready to run Windows 7, there’s a quick way to do a simple check.
Just download, install, and run the Windows 7 Upgrade Advisor. You’ll get a report telling you if your PC can run Windows 7 and if there are any known compatibility issues. If an issue can be resolved, you’ll get suggestions for next steps. For example, it may let you know that you need an updated driver for your printer and where to get it.
Note: Information about your PC will be sent back to Microsoft; however, no information will be used to identify or contact you. For more information, read our privacy statement.
Before you begin
Before you run the Windows 7 Upgrade Advisor, be sure to plug in any USB devices or other devices such as printers, external hard drives, or scanners that are regularly used with the PC you’re evaluating.
Download the Windows 7 Upgrade Advisor