shadow copying and updaters

Question

Hi,

Im trying to work an automatic update process in to my application.  I have read a lot about the method of creating a seperate project within your solution that essentially shadow copies your dlls and then launches the main application from a new appdomain, so that the main app can then overwrite the original dlls to update (with its update logic written in).

Im not fully sure im understanding this correctly.  My question is that if you have a seperate exe (a project in VS with just 1 class in that has a main and launches the shadow copy appdomain), then why do you need to shadow copy ?  As your running this seperate little exe, and your main application files are not locked or loaded?  Couldn't you just do the update there ?

Any pointers on this or insights would be great !

Thanks