You can install whichever Windows version you want, provided your system will support it. If you upgrade from Vista though, you'll need to purchase the upgrade or full version of the new OS.
See this to check for compatibility. This is for W8, but you can check the site for W7 compatibility also:
You can install whichever Windows version you want, provided your system will support it. If you upgrade from Vista though, you'll need to purchase the upgrade or full version of the new OS.
See this to check for compatibility. This is for W8, but you can check the site for W7 compatibility also: