I ordered this software to install with Windows XP. After installing it wouldn't work. I contacted Edmark and they said it was not XP compatible. I tried to return to Overstock but was told that you cannot return software. They did give me a gift certificate to be used toward a future purchase but it shouldn't be advertised as such if it isn't. I have had experience with some of the other Mighty Math games and they have been great. I just wish we could have used this one.