@matthew yes that would be the most IDEAL situation if you have time and oppertunity for it.
better would be that the installation detects the old version, runs the uninstall tool and reboot and starts the installation then
@mfrs strange so far i have had this with all the clients i tested (about 15) with selfdefense on it fails (several attempts on the same machine too), without it runs perfect directly
Its probably still worth for the Avast team to look into this for i believe there are still (bigger) companies that run the 4.x and 6.x client that want/need to upgrade to 7