The most imortant TFS configuration files to examine are the:
1. Data Tier: TfsIntegration database, specifically the tbl_service_interface table.
2. Application Tier: web.config sharepoint file located at C:\Program Files\Microsoft Visual Studio 2008 Team Foundation Server\Web Services\
3. Application Tier: msiproperty.ini file located at C:\Program Files\Microsoft Visual Studio 2008 Team Foundation Server\Microsoft Visual Studio 2008 Team Foundation Server - ENU\
Most problems with TFS migration can be resolved by examining the contents of these tables and files and correcting them manually if necessary.
The TFS utilities like tfsadminutil.exe are provided to automate the updating but they have a lot of dependencies that can cause them to fail.
It's a good idea to know where the low-level configuration settings are stored anyways.
Good luck. Anthony Maw, B.Sc., MCSE, Vancouver, Canada
tel/sms: +1 604 318 9994
anthony@maw.bc.ca
anthonymaw.com