Ok Deadfred;
Are you running any other firewalls apart from XP? If so, turn off your XP & configure your other firewall for LW:
http://www.limewire.com/english/content/firewalls.shtml
Configure for port 6346, then go & check what port LW's using now. If it's a different port, change it to 6346.
(tools > options > advanced > firewall config will tell you the port LW's listening on, 'apply' after change) Now do this test:
http://www3.limewire.com:6346
**I think this is right, someone please correct me if I'm wrong!
I can't find your modem details anywhere for use of UPnP or internal firewalls...do you have a separate router?