At this moment, I know that it is possible to emulate those Vista only dialogs on Windows XP. JSDialog is perfect for Delphi but for .NET, there is no such a thing.
I have been using Vista_API library for a few months but it’s command link support is not yet perfect for Windows Vista Home Basic (its ListView and TreeView support is great). Today I found this article, and its implementation is OK on Windows Vista Home Basic.
I will add those dialogs to GrapeVine Final. Stay tuned.