Also note that both computers must be set to allow remote assist (start > controlpanel > system > connections).
If that is set and windows messenger is installed you can do a remote assist by going to (for MSN 7): tools > start activity > remotecontrol (in convowindow).
For more info see:
Win XP - using Remote Assistance
If you don't have windows XP you will need Remote Desktop Connection Software (for: Windows 95, Windows 98 and 98 Second Edition, Windows Me, Windows NT 4.0, or Windows 2000). When run, this software allows older Windows platforms to remotely connect to a computer running Windows XP Professional with Remote Desktop enabled. Info and download
here.