Bill,
IMHO you should pause to decide whether you want to create another Windows app or follow one of the current trends- e.g. a Browser app or a Winforms app. Each of these has advantages and if you want to bounce some ideas, people here are well-equipped to assist.
You also need to decide how you want to store data. Dbfs may work really well for your customers, or some of them may expect a proper client/server database. You can do both as long as you plan it in from the start. Again there are lots of people here to help you on this issue.
Regards
j.R
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1
