Only if you have a current, valid, fully updated Windows 7/8/8.1 license.
If all you have is the current Windows 10 Preview...you will have to buy a Windows 10 license.
Only if you have a current, valid, fully updated Windows 7/8/8.1 license.
If all you have is the current Windows 10 Preview...you will have to buy a Windows 10 license.