MSDN subscribers can download evaluation VSTS VirtualPC images here: http://msdn2.microsoft.com/en-us/subscriptions/default.aspx.  Those will require keys.

 

You can download a VirtualPC image with hands-on labs from the 200-level Team System training here: http://www.microsoft.com/downloads/details.aspx?FamilyID=527e2a17-1dea-4d0b-9484-6ae43d00e570&DisplayLang=en.

 

There are a list of trial version (VSTS, TFS, and VirtualPC images) available here: http://msdn2.microsoft.com/en-us/teamsystem/aa718667.aspx