Helpdesk app suggestions

I am currently running DCL http://dcl.sourceforge.net/index.php on Suse Professional 9.3 machine inside our private network for our helpdesk app. And I am looking for something better.

Could I get some suggestions on better opensource helpdesk web apps that can do the following:

-trouble ticket
-bug reporting
-email notifications to creator and any other optional person(s) with watches
-run on Windows, IIS6, mysql, PHP or ASP
-creation of tickets via email… i.e. email to help@company.com will automatically generate a trouble ticket
-Reports!
-etc. etc. etc.

Any suggestions are greatly appreciated.