I've seen the same problem where no one is able to upload from me. I'm not behind a firewall either, just directly connected via cable modem to the TimeWarner RoadRunner ISP. Not one person has been able to download any of my shared files although I've seen many attempts. Something seems broken to me. I'm wondering if one needs a particular version of Java on the system for Limewire to run properly?

BTW, I have tried limewire behind a Linksys router/firewall and to get that to work go to advanced setup then to the forwarding tab and forward ports 6436-6451 BOTH to whatever IP address your system has on the LAN side of the router (on Windows one can run winipcfg to see this). You'll also need to configure limewire in the advanced/firewall setting and select "force ip address" and then fill in the address that the ISP has assigned the Linksys router (the WAN address). Look at the status page on the Linksys router admin webpage to see that info.