Here is what I had to do to get rdesktop to connect to XP Professional installed on VMware Workstation 6 running on Feisty.
In the guest XP system added a password for my account and turned on Remote Desktop in the System control panel applet on the Remote tab.
/etc/vmware/vmnet8/nat/nat.conf and added the line
3389 = 192.168.72.128:3389
Then I edited
/etc/systl.conf to change the IPv4 forwarding line:
# Uncomment the next line to enable packet forwarding for IPv4
Then I rebooted.
Now I started VMware and activated the guest XP system. Now the command:
Works as expected.