Remote Assistance

Hello, I am currently running a Red Hat 8 workstation as my help desk machine. I have users that are at a remote location down the street that are currently using Windows XP with Remote Assistance turned on. I use rdesktop to remotely control their desktops and occasionally their servers when I need to work on them. When I do rdesktop to their machines it locks them out, I get to view their screen and then they have to unlock the XP and then I get kicked out. My question is this, is there away to use Remote Assistance on a Win XP professional machine from a Linux workstation while both users can control the desktop at the same time so I can help them with their problems. Any help would be greatly appreciated.