Oldest avast! 4 that I found on Wayback Machine!

Avast Free Antivirus / Premium Security
1

avast! 4 Home: http://web.archive.org/web/20021223034630/avast.com/iavs4pro/setupeng.exe
avast! 4 Professional: http://web.archive.org/web/20021223034942/avast.com/iavs4pro/setupengpro.exe

Please note that avast! 4.x came out on December 18, 2002 but the oldest setup archives of both avast! 4 Home and Professional were both archived on December 23, 2002.

2

Doesn’t matter that much, being able to find an old avast version, there are no VPS Updates for avast4.

3

Is this the one with the notifications in that great German accent?

4

I didn’t look but there might be a link for avast sounds somewhere in this pdf: https://files.avast.com/files/manuals/user-manual-home-eng.pdf

5

Are you looking for the old avast! sounds, try this:
AvastSoundsAndGif.zip > https://drive.google.com/open?id=0B-vSic0iJgyeYnVjOHVadERHeDQ

6

Nice, got a machine to install on and just take a walk back down memory-lane. ;D

Edit; I still have an Avast Pro Antivirus v.4 License File