yes it can be difficult at work. At least try configuring the XP firewall manually, Windows Firewall - LimeWire
You can also try connecting thru a different port: between 49152 - 65535 are good ones to try. To check open & closed ports, you can try these port checker sites: Port Authority, for Internet Port 6346 ______ Shareaza Connection Test A
http://koti.mbnet.fi/gfactory/ctest/ ______ Shareaza Connection Test B

If you can find a port open, use that for listening thru in LW settings; Tools > Options > Advanced > Firewalls.