Yes I know that, but as I have software that has issues with Win XP SP3 (separate problem). I need a virus scanner to replace Grisoft AVG as that one is failing to install on SP2 as well. So I need to know if it is know answers to original questions.
Until you install SP3 your OS is a bleeding security hole that no antivirus can prectect you from. Keep in mind by Q4 Microsoft is stopping XP Support.
avast v8.x minimum OS requirement is still Win2000 (yes, some features won’t work on Win2000 or WinXP SP0/SP1: e.g. autosandbox, sandbox, safezone; you’ll have slower file-system shield, etc). Official note about XP SP3 is not correct (there’re still some win2k users on this forum). As for avast 9.x, users with Win2000 won’t be able to install this version – we’ll use a newer development kits which can’t produce a code which can be executed on Win2000, but XP SP2 should be still supported. Our statistics are as follow: we have 33% XP users (22% with SP2, 78% with SP3).