This is an old thread - I know, but it is still current as it is still on the first page of this forum ( wish CG had a Metro forum ), anyways...

You see, the problem is that WIndows 8 apps works in a sandbox environment, so you could never really truly launch an external app as you would ( in earlier VB versions ).

You may want to look into the Launcher class(es), as AFAIK, the whole ability for launching processes etc will eventually not form part of the Win 8 programming infrasturcture.
Yes, there are workarounds, like this one :

http://www.codeproject.com/Tips/4225...ows-8-Metro-Ap

But, it is far too 'complicated' IMHO