I'm developing my apps in VS.NET 2008 on Win XP SP2 32bit and I'm not familiar with how these applications run on 64bit systems like Vista, 7.

Do I need to build my app on 64bit system with x64 version of Visual Studio for apps to run correctly on this systems? Is there some kind of pre-build compatibility option for application to run on 64bit..?

Here's one of the problems...related to databases, on Vista 64bit app reports error "The Microsoft.Jet.OLEDB.4.0 provider is not registered on local machine"

If you understand what I'm talking about, please help.
And what are the things I must take care of when building apps (simple, only reading/writing to MS Access databases) to work on both platforms?