You should probably configure one firewall for LW, rather than turning them both off. I'd forget about the XP & just configure Norton f/wall.

Your modem supports UPnP. You'll have to have it on in the modem & in LW (tools > options > advanced > firewall config. Tick 'use UPnP' & apply). This thread has firewall and UPnP info:
http://www.gnutellaforums.com/showth...threadid=51357

And as for Tiscali, they might be a problem. See here:
http://www.gnutellaforums.com/showth...threadid=33712

Try & get an answer out of them re blocking p2p