Just downloaded 5.0, said it was finished. I was using the free version on this computer for the last four years. A window keeps popping up saying to uninstall current version. I select cancel and it says - are sure you don’t want to continue setup? Do I need to continue to uninstall the old free stuff? Sorry for the very basic question but I’m not very computer savy, not at all. Thanks in advance. 
When you install the new avast 5 it will uninstall the old 4.8 automatic …( short version… ;D )
The avast 5.0 version can’t be installed with avast 4.8 installed. The Installation process of 5.0 recognises you have 4.8 installed. The installation process will retain the registration/license data of 4.8, uninstall 4.8 and finally install avast 5.0. This whole process is very fast.
I select cancel[b]If you want avast!5 installed, you have to allow the process.[/b] :)