>Distributed as a CD-ROM. So there would be installation issues to be considered.

Excuse me for labouring the point but why distribute a CD? Advantages of an on-line approach:

- ZERO installation - users go to a URL in a Web browser
- No mailing costs or customer support to deal with wayward CDs
- Eliminates the chance of someone hacking your database on the CD
- Continuous functional and content enhancements can be rolled out to all users immediately
- Potentially accessible from a wide range of devices (PocketPCs, PDAs, Web phones, etc.) not just PCs
- Better revenue control - no possibility of someone duplicating and distributing your CD

The only real downside is that a Web connection would be required. But even dial up would probably be OK; you seem to specifically want to limit how much data a user gets at one time and with a well designed Web app my guess is your bandwidth requirements would be pretty low.

Superficially, your situation appears tailor-made for a Web solution. If I were you and I didn't take this approach, I'd be worried my competitors would.