This is all over the web… but can I just say how much I love this tweak?!? :-) If you’re anything like me you probably connect to any number of different TF servers in the run of a day, and having Team Explorer not auto-connect when it starts makes this process sooooo much easier.
To make this happen, add a DWORD value called "AutoLoadServer" under HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\8.0\TeamFoundation (for 2005 – change this to 9.0 for Orcas). A setting of Zero means do not reconnect automatically.
LOVE IT! <g>