Well version 8 is compatable with Windows 2000 SP4, there are 2 bugs that seem to have risen from this version, yet it involves the The ScRegSetValueExW error, but to make note of the Bug it also Corrupts the Event Viewer "System Log" and disables MMC.exe to access the Services Consule which is not normal of Avast, although because NT 5.0 is being fully discontinued this June for support, I figure this bug might not be corrected.
Otherwise than that, it's scanners are more improved, even in the Boot up mode.