The real attacks on a LAN are going to come from the network side of things. So the biggest thing to do is always have your Firewall enabled. Whether it be Windows firewall or some other third-party one. Antivirus is fine too but that's more related to stopping internet or e-mail based hacks.
Try to use secure links (https://)
and e-mail (SSL) whenever you can. Because most systems and routers cannot protect you from a man-in-the-middle attack, where someone on the university LAN could hijack the connection between your computer (or router) and the gateway router. Then they can steal your passwords if you don't use secure links (a.k.a. encryption).