Meh, this question is probably been asked before but i couldn't find any relevent results searching. A friend of the mine is building me a computer and to curb costs i was wondering whether i could take the windows xp home edition cd, from old pc, and install it on my new one using same key, my old computer will be rendered useless anyway as we are using parts from it. Then when xp says to activate it over the net, will it let me? I am guessing i will probably have to ring up microsoft to sought it out. Or would it be better just to buy the OS again.