What sort of project management software should I use for a small team?

I'm currently working on a project with about half a dozen other people. Currently we are using sharepoint to track assignments, issues, the overall timeline, etc... The problem is that sharepoint works but is overkill.

I'm just wondering if anyone knows of any good software for a small team would allow us to assign tasks, track issues, and give a good view of overall progress (my boss likes the gantt chart in sharepoint for this).

Thanks.

edit: Sorry, forgot to add that I don't think an online system is an option right now.