Use the following url in IE. It opens up part of the help center where you can offer someone remote assistance. I use it at work, however I do not know how well it works in a non domain environment.
[hcp://CN=Microsoft%20Corporation,L=Redmond,S=Washington,C=US/Remote%20Assistance/Escalation/Unsolicited/unsolicitedrcui.htm]

Or you go to Help and Support under XP, select Tools and there should be "Offer Remote Assistance". Or search for "offer remote assistance"

Badri