Mac OS doesn't support .NET or VB, although there is an alternative .NET
implementation that's being released soonish if it hasn't already, called
Mono, which may work under Mac OS. I don't know if Office on the Mac
supports the cut-down version of VB (VB for applications?) but that won't
let you create a full application in any case.
As far as I know the main choice for cross platform programming at the
moment is between Java and C++. Java's advantage is that it's fully cross
platform. We use C++ because we use highly optimized maths libraries, but we
have to write platform specific front end code.
Whichever you choose I'm not sure if you'll be able to interact with Office
using the same code for each platform, but I've never tried that.
Good luck!
Steve
