I need the url to download the Free Avast version 4.8 from the official site http://files.avast.com
Do not double post 
There isn’t any.
http://filehippo.com/download_avast_antivirus/
Why would you want/need an old version?
May be jppm30 think version 4.8 can running fast on his old comupter.
On contrary, version 6 is lighter.
But, of course, it requires Windows 2k/XP.
I use also free avast4.8 for my old mobile note Win-98SE (memory 256MB only) with ZoneAlarm to keep this old machine alive considering possible case of emergency to evacuate my main machine Win-XP someday. This old machine still works perfect with word, excel and e-mail use, and internet in case of need. Of course it takes dayly quite a time to update vps, but it is worthy to do.