Enable Remote Desktop on Win XP Pro With Firewall enabled.

1. enable port 3389 to pass through the windows firewall (that is the port that RDC uses)
2. enable remote desktop on each of these PCs for domain admins only.

thats it.

Can I do this with a Group Policy?

Yes.

Computer Configuration>Administrative Templates>Network>Network Connections>Windows Firewall>Domain Profile ::

Windows Firewall: Allow remote administration exception = Enabled.

It did not do it in my envirement, but the following worked:

Computer Configuration>Windows Settings>Local Policies/Users Rights Assignment:
     Allow log on through Terminal Services - Domain/Administrator

Computer Configuration>Administrative Templates>Network>Network Connections>Windows Firewall>Domain Profile :
      Windows Firewall: Allow Remote Desktop exeption - enabled

Computer Configuration>Administrative Templates>Windows Components>Terminal Services
      Allow users to connect remotely using Terminal Services

I needed all theses settings for the GPO to work.

Well, the first and last elements would have been automatic had the checkbox for Allow Remote Desktop in System Properties was checked.  I had assumed this was already done.