On a slightly related topic, I'm new to .NET and want to expose some C++
classes for use within VBA in Excel. What is the best way to accomplish this
(COM, for example)?

"DM Unseen" wrote:

If XLL is no option, COM will do, as will VBA for that matter.

I would suggest start prototyping with VBA and look how fast it is. COM
will not do a lot better unless some internal calculations can be
optimized. This depends on the type of calcuation. VBA can be protected
from endusers, just not from XL pro's;).
To prevent code misuse you can scramble your VBA code, this will really
deter code stealers! Porting from VBA to VB COM addins is not that
difficult, so you can always do this when it is required.

DM Unseen