This sounds like a firewall issue.
Limewire and other P2P clients use separate ports from browsers and the like, which are on port 80.
You say you're back at school - are you on a campus network? If so, then you're up the creek, my friend. School networks often block these ports specifically to stop filesharing. Find another client that the uni sysadmins don't know about, or browse your local network for shares - high speeds and other people have a lot of stuff!
If you have access to your router, you need to set up port forwarding. Figure out which ports LimeWire is trying to use (should be in the preferences, or the online documentation) and have the router forward those ports to your machine - you'll need a static IP for that, post back here if you don't know how to do that. Or google and find out yourself - that's how we learn! :P
Let me know if you run into problems,