yes it will take xp off the other one I think cause its only legal to have xp on 1 machine at a time but if you aren't going to be using that computer then you can take it off
This is the method I'm familiar with: Install XP on your new computer. You'll probably get a message from Microsoft telling you that you already have XP installed on another PC. They'll give you a phone number to call to activate XP on your new computer. Once XP is activated on your new PC, you probably will not be able to use it on the old one. Does that make sense? Someone else may know a better method.