Is it possible to connect to 2010 TFS from Visual Studio 2008 Professional
There is an update VS90SP1-KB974558-x86.exe that is targeting VS2008 client, but that update did not recognize Professional version of VS2008.
Although TFS2010 is part of professional MSDN subscription
This blog post should get you going.
Quoted from post:
You have to install Team Explorer 2008 over your VS2008 Professional SP1.
You need to reinstall VS2008SP1 to update team explorer.
After that you have to install Visual Studio Team System 2008 Service Pack 1 Forward Compatibility Update for Team Foundation Server 2010 (Installer) from this link.
When you connect from VS2008, you need to enter the full URL (ex:http://tfs2010:8080/tfs)
The order is important and you have to enter the full URL in 08.