some question about virtualbox over ubuntu

[loody]

hi all:
My environment like below:

Pc A, ubuntu 10.10, runs windows server2003 in virtualbox4.02.
Pc B, xp
Pc C, ubuntu 10.04

I have some questions:
1. is it possible for PC B or PC C to remote controll windows
server2003 in vritualbox 4.02 on PC a?
I found server2003 default use rdp, remote desktop protocol, for
remote control but I found pc B and pc C cannot find the daemon when
connect to pcA.

I guess maybe the problem comes from the setting of the network
interface in the virtualbox.
(I choose NAT right now.)

appreciate your help,
miloody