i also did it in sp2 firewall jst in case.
Aha! First you need to decide which one you want to use! You either embrace M$-XP, build in, software firewall or the one build in to your router.
My suggestion is to disable the SP2 firewall. It is my understanding that it is not 'all that' anyway.
Once you have done that, try again.
I am not using D-Link so cannot comment on how to do port forwarding.
This is how I do it in Netgear (once logged in to the 'virtual server'):
1. Create a new service - chose TCP/UDP or both, then entre your port (start and end port are the same if you are using just one port.).
2. Add an inbound service - chose the newly added service created in the previous step. Then I chose 'Allow by request, otherwise block' and send to a new LAN IP address (something like 192.168.0.X).
And that's that.
As I said before, I have stopped using 'softwalls' since I got my router.
When I do get a NAT error, which hardly ever happen (a bit tlike huricaines in Hereford), I normaly restart the application and it seems to work....