Since I recently went through this I figured it would be worthwhile to compile the downloads, regedits and other steps into one location.

Downloads for Visual Studio 2008

You’ll need to download and install the following for Visual Studio 2008 in this order. You may need to reinstall SP1 if you already have it installed to ensure TFS 2008 behaves properly:

Adding the TFS repository

If Visual Studio 2008 will let you, you can now add the server with the following format:

https://tfsserver:port/vdir/projectCollection

If you get TF30335: The server name cannot contain characters ‘/’ or ‘:’ …:

Open Regedit and browse to HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\9.0\TeamFoundation\Servers
Add a new string value:

Name – Friendly name that VS2008 will display.
Value - https://tfsserver:port/vdir/projectCollection

Important Note: In VS2010 you don’t have to specify the project collection to connect. Please be mindful that this is necessary for 2008!

Resources

http://blog.hinshelwood.com/connecting-vs2008-to-any-tfs2010-project-collection/
http://www.jmedved.com/2009/11/visual-studio-2008-and-team-foundation-server-2010/
http://stackoverflow.com/questions/1925512/visual-studio-2008-cant-connect-to-known-good-tfs-2010
http://social.msdn.microsoft.com/Forums/en-US/tfsgeneral/thread/54c862f1-d93a-4030-8972-60d3dda7d4d4/

Connecting to TFS2010 with Visual Studio 2008