I am using Avast 4 fine on my Windows 64-bitVista partition. However, when I tried to install it on my Ubuntu Linux one (again, 64-bit version) using the DEB file I get a message that it is the wrong architecture/i386.
yes, it’s only about telling the packaging system that you really want to install the application, because it is labelled i386 (IA-32, 32-bit, and not x86-64).
you must have the IA-32 backward compatibility package (libraries) installed, to be able to run such apps.