Windows 7: How do I customize (specify) my own Windows Explorer?

Hello,

I use Directory Opus as my file explorer and have been doing so since Vista.

In Directory Opus, there is a configuration setting to replace Windows Explorer. In general, this does work; however, there are numerous occasions where Windows 7 will still launch Windows Explorer or set it to the default selection in context sensitive menus, for example. Vista never did this.

I'm thinking that some registry setting somewhere has the "explorer.exe" as the value and that's what it launches. I'd love to be able to replace the "explorer.exe" with "...\dopus.exe".

I just want Windows to always launch Directory Opus instead of Windows Explorer. Do you know how and where I make that configuration?

Thanks!