Q

o I need to set up port forwarding on my router to get Remote Desktop working even if I am only using it internally?
A:No, you don't...since you are on internal network....all the ports are open for the IP address on that subnet.
Q

o I need to specify the User, Computer name and Work-groups (these have not been properly named - so should the work-groups be the same? I haven't managed to 'see' the 'other' computer in any other way yet.
A:You don't need to be on the same work group in order to do a remote desktop....but being on the same work-group only will help if you do a network look up of other computers.
Q:I have added the IP's to be allowed for TCP in/out in the PC firewalls (ZoneAlarm on one and Comodo on the other).
A:This is a good step to right direction.
Q:Can anyone help me with all this? Give a me check list of what I need to configure, or check - is there's anything I should NOT do?
A:We all will try to help out

, just do a bit of reading on the following site, it will go a long way to help you connect through remote desktop.
http://www.windowsnetworking.com/art...ws-XP-Pro.html
I am also considering using a different program, such as TightVNC (free)...that'll be fun. I'll be testing a few other free VNC apps to find out which is the best to used to help friends with their computers outside the home network.
TightVNC is not bad because it's free other wise I wouldn't use it...it's not as user friendly as "Radmin". (
www.radmin.com)
Cheers