Ah, well XP home doesn't come with any built in software for letting others take control of your PC so you'll have to use some third party software. The option I'd take would be to use VNC - but then I'm mainly a *nix person so that's more my territory. If you really want the simplest route then www.logmein.com
would be a good bet, the free version will suffice and it's probably the easiest solution out there. Literally install a piece of software on the machine you want to control and then fire up the website on the other one and control it.