are you specifically wanting to use remote assistance.....if not i would suggest the following...
have you tried remote desktop (all programs --> accessories --> communications --> remote desktop)
you'll need to make sure the computer is remote desktop enabled (control panel --> system --> Remote tab) "allow users to connect remotely"
then simply enter the computer name you want to connect to
**edit** FYI....RDP is only available in XP Pro (which you stated you have)
Edited by bama_fan, 12 November 2008 - 03:02 PM.