Cant Remote Desktop to Server 2003

i have a windows XP Pro laptop and I remote to 3 of my Win 2000 Server machines with no problem. I have 2 2003 Server machines that I can’t seem to remote into. I can see the machines on the network and get to shared drives on each of the machines. When I remote in I get an error that says: The client could not connect to the remote computer. Remote connections might not be enabled. What do I have to enable on the servers? Thanks….