Where does the VFP6 'Active Document' fit into this?

Forgive my being a little nieve but i'm in the same position (huge existing VFP app, need to convert onto the web) and from initial investigations the active document, instantiating my app in the 'run' event seems (on the face of it) to do the trick.

Am I missing something, is there a fundamental drawback to using this method? The documentation seems pretty thin on this subject.