As far as I'm aware,
AshServ.exe is the actual antivirus program itself.
AswUpdSv.exe is the updating service.
AshDisp.exe is the interface that provides you with access to the scanner GUI and the taskbar icon.
I believe these are necessary for Avast to run.
As you can see,these are the features that you are asking for, you have stopped the other resident protection providers.
Please correct me if I'm wrong,
Hope this helps,
-Scott-