Which Helpdesk Package?

I work for a University and need to choose a Helpdesk package to help with logging calls. The Department is 18 strong, with 3 of those on the help desk phones. We also employ 7 student PC techs. We need a package that will let us create a knowledgebase, keep track of calls, track who is doing what, track inventory, has a check out for equipment, and has a web plug-in so that functions are available on the web.

What helpdesk are you using and do you like them?