Sedi1980

OK I am so lost. I have been reading a lot of things about hot to go from Vista to XP and I cant seem to figure any of them out. I was wondering if anyone has a fast way to do it for someone who doesn't get all this stuff. I am using an XP upgrade disc and I am getting the error that it cant be installed without a certain version of windows but I know it can be done because I did it when I bought the HD. Any ideas?