OK, i just built a new PC and the problem is while i was gone my brother tried to install Windows XP and it got installed and everything but the thing is that the one he tried to install was from his friend and something is wrong when i try to activate windows i call and try to activate it like that and the key they give me doesent work so i have no clue how im going to get past this i have the copy i bought brand new not even opened yet .
Just do a re-install from the beginning with your genuine disk. Make sure bios is set to boot from CD and load it in CD drive before you boot. When you get to part where it gives option to delete partition and then format just do exactly that.