> I want a C++ program to copy and install an add-in (.xla) in Excel. But I
> don't want to start Excel to achieve this. In fact, users should not be
> confused with installation questions and actions. Just put the file in a
> directory and have Excel open in automatically as an add-in next time it is
> started. How can I do that?
> 
> I assume I will have to manipulate an .ini file and/or registry settings.
> Can I do it the same way for each of the versions 5, 7 and 8?

Jurgen, with Excel 5 any Excel files in the start-up directory are opened 
with Excel. I keep a "personal" macro add-in file (xla) there to keep 
handy functions that I use. Add-ins loaded in such a manner do not show 
up in the Add-In Manager nor can they be unloaded using it. You can 
unload them using VBA code and can even include code in the add-in itself 
to close the file and remove from memory, I use this technique with some 
other add-ins.

Tom