TFS 2010 - you should have the right to use it for 5 people, otherwise ther are various cheap offers for companies.
Set it up on a decent computer with virtualization - one vm TFS, one SQL, one (possibly) build (only).
Source control with SQL Server behing.
Integrated work item tracking
Can integrate continuous integration with testing etc.
Can integrate sharepoint for documents.
Easy to set up in the 2010 version ;)
