project management/workorder tracking system

anyone know of a good issue tracking app thats open source?
we currently use trackIT to keep up with work orders, but
have been unhappy with how slow it is at times and the fact
it is only good for windows and IE.
we need something flexible, open platform (for mac and linux
use), open source preferably, with
a searchable database, and maybe even some inventory functions.
we are currently looking at RT and OTRS. are these ok, or is there
something out there thats better. many thanks for any imput
you guys can give.