It kind of depends on your definition of 'interactive.' DVD menus are rather limiting and you will have to be creative and make compromises every step of the way.
If you want your butttons/elements to 'fly in' you could create a movie that, when finished, jumps to the menu. The menu could either be a simple menu w/overlays, or a layered menu.
A layered menu will look the best and offer the most flexibility as far as graphics go. You will, however, lose the ability to have a movie as the background, play sound, and will have a bit of a delay while changing button selections.
A standard menu will still allow you to have a background movie, sounds, and will be very responsive to user input. Overlays, however, don't look very good and you will likely want to create custom shapes in Photoshop.
Read up on menus and layered menus in the DVD Studio Pro manual for more on this. There's really no way, that I know of, to have a truly interactive menu, i.e. where buttons move around within the menu.
