>Well, middle-tiers are mainly business rules specific. COMs in my understanding are independent programs that don't rely on outside programs. Instead, outside programs execute them and not the other way around, right?

Take a look at this link to understand the Windows DNA as it relates to the n-tier development model:
http://msdn.microsoft.com/library/psdk/bdg/bdgtec01_8q3w.htm

If you follow this architecture (which is the way most modern development is going) the guts of your application is in your business layer(s). The UI never touches the data directly. (So DE and Forms are a none issue for any serious development project. I no longer touch the DE.)