Depending on the version of Windows you’re currently running, installing Windows 7 on your PC may be a lengthy process. Run Windows 7 Upgrade Advisor to make sure your PC can run Windows 7, and then review the information below prior to buying or installing Windows 7 on your PC.
Use this chart to determine whether you should do an upgrade or custom (clean) installation.
To upgrade an earlier operating system than Windows XP (for example, Windows 95 or Windows 2000) you will need to purchase a full license of Windows 7 and perform a custom installation.