Depends.
I seem to recall the user account has to be flagged on each system a certain way, ie: allowed to remote in. I'd have to check my work PC. which I'd have to rdesktop TO. But I don't have it's name/ip address here, so I can't look.
Ask tomorrow if you need the specifics.
On the other hand, you'll love it compared to VNC. VNC protocol SUCKS (especially when dealing with Windows as the host) as compared to RDP.