XP system uses the method of remote control desktop tool with self
1. Let your friends set this up, right click My Computer-Properties-remote-allows users to remotely link to this computer so you can connect to your friend's machine remotely.
2. You do this, start-All Programs-Accessories-Remote Desktop Connection, open the input of your friend's IP, enter the username and password can be linked.
The premise is your friend has fixed IP, if your friend uses the route to surf the net, needs to set forwards 3389 ports to your friend machine's IP, in addition the default administrator empty password also does not allow the landing, or modifies the Group Policy, or adds the password for this user name.