I'm using a G4 with an external DSL modem that uses NAT and other firewall related stuff. I've made the appropriate pinholes, and even at times, disengaged the firewall to make sure that it was not hindering limewire.

I've noticed that when operating as an ultrapeer, my connections will either be primarily incoming, or outgoing. The opposing will usually number less than 4. Regardless of ultrapeer or leaf, most of them are 'one direction'. Maybe I don't understand the incoming, outgoing status, but I would imagine being connected to all incoming clients would hurt the network! Please reply if you understand why.