Big problem pls help: I got this new computer with windows 7 home on it as the factory default windows version. I did not like it so wanted to go back to what I was used to which was XP so I put in the disc and went through the procedure to put it back on but it seems rather than go over the factory windows 7 home, I think it actually installed next to it and not over it and is still not the main Operating System. I did something wrong obviously but now I need to get back to the original factory windows 7 but don't know how. Pls someone help. What have I done wrong? thx.