while you may or may not be able to use your install disk,you will need to purchase a licence.this is getting a tad difficult with windows 7.if you can,buy a windows 7 disk and licence from a reputable source.then you can use the free upgrade to windows 10.despite all the conspiracy theories about win10 its actually a really good os.at any rate,you have until next july to decide,and can run 7 in the meantime.if it becomes difficult to find a legit win7 you can always buy a win8.1 from microsoft.