You could consider using SharpForge as an open source alternative to VSTS. It's a fairly new project and still in beta but check out the screen shots of where it's heading.
SharpForge 0.5( http://sharpforge.org/ ) is an open source, c#, dot net 2.0, project management web application. It supports multiple portals, multiple projects, subversion administration, work item tracking, project forums, release management, subversion wiki, subversion browsing & news feed aggregation.
Similar to SourceForge, TFS or CodePlex but for your own team or organisation. The software is released under the New BSD License.