As an exercise I have just tried to find it again myself from the Products page and even though I got further than yesterday I still have not landed at the page you sent me.
Go to the avast home page:
http://www.avast.comOn the left tabs click on "Home and home office".
Under "avast! Free Anti-virus" click on "Learn More".
Scroll down to the tab sheets. There should be 1 white tab and 3 black tabs:
"Why choose this product?"
"Technology"
"Compare products"
"Version 4.8"
You will probably be on "Why choose this product?".
Click on the "Version 4.8" tab.