How to determine version of Access from .NET 3.0 app?

I need to be able to use PIA's to invoke Access 2003 OR Access 2007 from the
same .NET 3.0 application.

But I would rather not have to include a reference to BOTH the 2003 and the
2007 PIA in my app (if that's even possible). Instead, I plan to implement
an interface layer that will dynamically load the appropriate PIA.

But how can I first determine what version of Access is installed on the
system, in order to then load the correct PIA? For example, I can't use the
version property of the Access.ApplicationClass, because to get to that
point, I already have to loaded the correct PIA. Do I have to enumerate the
assemblies in the GAC? Or something similar?

(forgive the cross-post, but I'm not sure whether this is a .NET or an
Access question!)