I guess one possibility would be installing a small database of some sort on the CD, and having Excel pull the data from it by ODBC. Of course you'd need whatever restribution licences that required and you'd probably need to install the ODBC driver, but then your database software would be able to limit access based on node locking, dongles etc.

Another route is to somehow transparently decrypt it by way of a third party program. The snag is, how to prevent the user from easily obtaining the decrypted file (bear in mind that excel would work with a temp file or something that they could get).

I can't see a way you can give XL access to the file without other programs being able to swipe (and thus copy) it too.

VBA scripts can of course be all disabled and the excel file cracked anyway. I guess you could code some VBA scripts which create some kind of view of the data, which are otherwise present anyway but encrypted. This VBA would then have to do whatever necessary to validate the licence - perhaps checking the internet occasionally for stolen serials which have been published - or something.

In any case, it sounds complicated, unreliable, and may piss the users off

Slarty