1GB Network card / switch upgrade causing Remote issue?

Recently upgraded my 5 pcs at work with 1gb network cards and with an 8 port ethernet switch (Netgear) everything has gone fine apart from that one pc is now not accesible for remote desktop function.
It worked fine on Remote Desktop before and the 3 other pcs running remote desktop also work fine.
I can not even access this with remote while in the office.
I tried the usual stuff firewall, port opening etc, but this has confused me.
All pcs running XP pro,
Ideas gratefull

Is it possible that for some reason it does not like the ip address assigned? Have completed a succesful ping to the pc.
This is not on a network but a shared workgroups system, There is no IT in our company before you suggest that!
Also not interested in installing a third party software package.

The pc receives 1gb, and works all fine just does not access the remote desktop

If pinging from and to the computer work fine, the assigned IP address can't be the problem.
I assume everything else works ok with this computer? You can print fine, share documents, browse the internet, etcetera?
The computer is still in the same workgroup as it used to be? The old network interface card has been removed completely?
If it does, goto the properties of my computer, goto the connections tab. Turn off desktop sharing completely. Reboot the PC. Goto the connections tab again, and turn it back on. Reboot the PC. See if that helps.

Did you replace the cable? Maybe you have a cable that is fine at 100Mbit but fails at 1000Mbit.