When you install PC-DUO on your windows xp system, you won't be able to do remote desktop to that machine anymore. It is because PC DUO modify the registry not to use msgina.dll. It uses PCIgina.dll. To remedy this issue, edit the registry:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
find: GinaDLL and change the entry to msgina.dll
ref:
http://support.microsoft.com/default.aspx?scid=kb;en-us;829715&Product=winxp
