DCOM, COM+ & Multitier Development concept question...

I have been developing multitier applications for the past few months, but I am finding it very hard to find web based articles or code to teach me the fundamental basics.
Although I know how to develop and deploy multiuser, multitier database applications there are still some questions I have, which have so far gone unanswered :mad:

Question 1: :confused:
With a small ( 1-2Mb ) application, or any multitier application the business logic tier is usually deployed on a server. I know that this helps maintainability and scaleability. What I don't understand, due to the fact I have found no evidence to support or condem it, is why the seperate user interfaces for each section of the application can't be included in the business tier. To me this would make more sense as if this has to change, and the client application is purely a "menu", the user interface for a percific class can change without affecting the clients machine. Oh, I am assuming everyone with be accessing the DLL from the same application and the same operating system, as I know that if accessing the DLL from different operating systems and clients is a bad idea if the DLL itself contains UI's. Apart from this can anyone shed any light onto this matter?

Question 2: :(
I understand that ActiveX EXE's are slower that ActiveX DLL's, but with the speed of todays machines does this really have a huge affect on the performance of the application? Apart from the fact that ActiveX EXE's run on seperate threeds and the fact they can be run as "standalone" applications, are there any other benifits, or hinderances, regarding using them instead of DLL's?

Hope someone can shed some light on these matters. It would be much appreciated...and I appologies for my spelling, sorry.

Regards,

Steve