You can follow the below steps to integrate VS 2008 with TFS:
Setting up the Team Explorer:
1. Download and install Visual Studio Team System 2005 Team Explorer.
2. Apply Visual Studio 2005 Service Pack 1.
Connecting to TFS:
1. Open Visual Studio 2005. Click "Connect to Team Foundation Server..." under the menu "Tools":
2. Click on "Servers...", then click on "Add...", enter the Server URL plus your organization ID on your TFSHosted account. For example: https://s01.tfshosted.com:443/tfs/105432.
If you have forgot the url, you can check it in the Hosted Portal.
3. Enter the credentials to log in:
4. Now you are connected to TFS and ready to work: