Thanks for the quick responses.

What confused me was this post of someone saying he had installed 7.0.1488 (although showing an Avast 8 UI obviously)
http://forum.avast.com/index.php?topic=122948.msg936310#msg936310

I did not update to 7.0.1474 because I run WinXP SP3, and 7.0.1466 > 7.0.1474 update was useful for Win7 or Win8 users only.
I will end up installing Avast 8 some day however.

By the way, I applied the Avast 7 patch to make the Script Shield work with Firefox 17 (FFx 17-ESR version in my case).
http://forum.avast.com/index.php?topic=109977.msg868918#msg868918
Do you know what versions of Firefox the ‘Avast 8.0.1488-Script Shield’ supports?