Which is the best free helpdesk software ? Which is the best free helpdesk software ?

Years ago I played around with IRM (I heard about it from someone I 'knew' in the IT dept. at Valdosta State, where I think the program started) when I worked as a tech for a school district which ended up going with some other costly windows friendly program (that is so memorable I can't remember the name) that I didn't like as much.

Anyway IRM is a PHP/MySQL web based system. The Valdosta State IT dept used to have a relatively unpublicized demo version setup, though I doubt that exists anymore.
http://sourceforge.net/projects/irm/