Hi Peter
I'd help, but your situation doesn't make sense: you see plenty of completed uploads but can't get decent search results?
The usual OSX connection problems (OSX firewall in System Preferences->Sharing->Firewall->New not opened to the Gnutella/Limewire network, router not mapping port 6346 to your computer) usually allow searches but not uploads. Look at Tools->Statistics->Advanced->Uploads to see more details on uploads than are shown in the Library Pane.
If you are finding mostly porn, you might be connected to a spam servent and that is flooding your results. LW throttles searches at ~150 results. Control-click the IP number of spurious results and you'll get the option to block that host, and turn on the porn filter in the preferences. More specific searches should work better too.

On OSX 10.2, LW 3.6.1Beta, and sharing 9K files as an Ultrapeer over a cable/NAT connection here, Nirvana returned 209 results very quickly.