Free server based Collaboration tools?

[radditsu]

Any one of you nerds know of a decent Project Managment/Collaboration tool...with private messaging...out there that I can drop on an Apache or IIS server. I would rather use SQL 2008 instead of MYSQL if possible.

Not opposed to an all Linux solution. Would prefer something I can setup on our existing IIS server.


There are a million of these things and not a damn website will give me a decent feature list.