So I went to a local thrift store today and I picked up a copy of windows xp home edition. The problem is I can't tell if it is a upgrade key or a install key. Because: It came with two discs. One was an upgrade disc and one was a install disc. (One was in the box and one was in a cd envelope.) The install disc is not reading the key so I'm assuming its an a upgrade key but I would like some others opinion or tell me if there is a way to tell. (Also it was a great deal of 3$ for the discs)