Remote to the 2003 machine that is your target, and then go to start - run "mstsc.exe -console" and create another RDP session to the same machine this time on the winstation 0 (console). You can also accomplish the same by remoting into a 'Gateway' machine and then opening RDP Console sessions to the other servers. You will need the proper permissions and Remote settings for multiple sessions, Google this if needed.
Anybody figure out how to move the mouse cursor around in rdesktop? With either a BT mouse (which sounds unlikely, given what these forums turn up) or with a keyboard? It sounds like turning on MouseKeys in Windows might work, but I don't have a numpad on my keyboard. Boo.