Make sure that you're only using 1 software firewall & that it's configured properly
Firewall setup

Do you see any green connection bars at all?
Do this test & see if it works
http://www3.limewire.com:6346

The problem might be an internal firewall within the router. Is your roomie using LW? If they are, do they have port forwarding set up? Read through the thread below, it's got lots of info about enabling UPnP & port forwarding to overcome router firewall problems
Connection problems? Check here first!

Does your school allow p2p use? Many don't... you might want to check with computer admin.

If you're still stuck, post back with your details

OS(Win XP etc)
LW & Java version (help > about LW & you'll see)
Firewall you're using
Modem/router brand & model
ISP
Connection type (DSL etc)
Where you connect from (home, school etc)
Are you sharing a connection with other computers
Is this your first try with LW