My new soruce control client hijacks Visual Studio default soruce control provider

The default source control provider links to Visual Studio is VSS (of course!). Howerver, since I installed PVCS Dimesion client for a different project recently, the source control changed to be PVCS.
It is not in my interest to use PVCS for the .NET projects I am working on. However, there is no way you can change it back to VSS from Visual Studio(it is not the tools|option|source safe menu.)
The only way to change this is from registry:

Run regedit. Browse to 'HKEY_LOCAL_MACHINE\SOFTWARE\SourceCodeControlProvider\InstalledSCCProviders', it should be a list of all installed SC providers there. Copy the Data (path) of the intended used source control provider, then use it to replace data of 'HKEY_LOCAL_MACHINE\SOFTWARE\SourceCodeControlProvider\ProviderRegKey'.

Maybe there is a switch program around? Sure I am not the first one met this problem. I will do one if I have time. Many thanks to Nick A. to share this.