Do this simple test for us. Using your browser go here:
http://www3.limewire.com:6346/ The page should say 'Your test worked!'. What happens when you go there?
There are more fixes to try here:
http://www.gnutellaforums.com/connec...t-connect.html
The info refers to LimeWire but is the same for FW
If you want to replace the gnutella.net file, the files linked to are fine to use in FW.
Try to find out which firewall(s) you're using. I don't use Vista, but maybe Control Panel will have an option (security, firewall etc) to show you? You can also hover your cursor over icons in your system tray - see whether any of them belong to a firewall.