My Mac's down at the moment, so I'm doing this off the top of my head and can't remember all the options! Have you made sure you're searching the right area? Are you searching the internet and not a local area network (LAN)?
Other general things to look out for: make sure you set your connection type to the relevant option (eg. ADSL) in the settings and make sure that you also are aware of the filters in the server list which might prevent you from seeing a server you are after.
Hope this helps, but let me know how you get on. It's a bit tricky doing this from a rusty memory!