Weird Wireless Ports Problem

I'm trying to open up a port for Azureus on my wireless network.

Connection: Ethernet
Router: Linksys WRT54GL

'Base' Computer running on XP. This PC is connected to the router. Its got McAfee's Antivirus and Personal Firewall. Im using Airport on my Macbook for wireless internet.
I've created a static IP for my macbook, and set port forwarding for port 50000. In the Azureus options menu, I've set it to use that port as well. But when I test it, it gives me a 'NAT error' ?
I tried using another port, but got the same thing. I used this port scanner, https://grc.com/x/portprobe=50000 and it showed that my port was in stealth mode, which confirms I have a NAT problem according to the azureus wiki.

I dont get why I have a NAT problem, I've created a static IP, configured the port forwarding, opened the port through McAfee, so what else could it be?

Thanks

is the port firewalled via some sort of software? make sure that in your routers settings both udp and whatever that option is gets checked off.
-chris

The port is enabled in McAfee, and both udp and tcp are checked.