Peter & Nick,

Thanks for the comments and information. It's become apparent to me that I
don't understand the problem well enough to make an informed, intelligent
decision. There does not appear to be a clear "correct" answer.

VB6 is probably the simplest solution, but if MS is not supporting it in the
future then this may have a limited lifetime and require another port in the
future.

Delphi may be an option, but I'm concerned about the compatibility with MS
and support. I prefer to use the MS advertised/supported/built-in tools to
minimize the compatibility issues.

Add-In Express looks useful but will be another unanticipated expense and
learning curve.

I've been told dot.net applications can be decompiled and do not provide
absolute security.

I still need to solve the installation kit/uninstall/licensing issues for a
non excel addin solution. The excel addin installation is simple enough and
I have a crude yet usable licensing scheme based on the C drive serial
number. I have some ideas on how to improve the licensing scheme and make it
easier to work with.

Another option I've considered is using a security enhancement tool for the
excel addin. The tool supposedly prevents most password recovery tools from
working. The tool also prevents the hex editor hack from working unless the
hacker understands the entire MS VBA protection scheme. Have you heard of
this or have any experience with this security enhancement tool? An excel
addin with this additional protection may be the simplest and most reasonable
solution.

I'm leaning toward the following solutions:

short term - use an excel addin with the additional protection.

long term - consider another programming language to create the addin. The
primary concerns are MS compatibility, lifetime/support, additional product
requirements (licensing, install, etc) and cost.

Please provide any additional suggestions/comments you have. I'm especially
interested in any comments you have on the enhanced security tool for an
excel addin.

thanks again.