careful i know windows 7 enterprise is EXCLUDED from the upgrade so do a little digging as to which copy to buy. walmart, amazon - doesn't really matter where you buy it just look around for a sale you can normally score copies for around 70 bucks. what you DONT want to do is go to one of the many sketchy websites that are selling licenses for 20-40 bucks. they are illegally redistributing keys that wont work.