WD is built in to Vista and 7 so avast! 5 disables the real-time scanning component when installed.
Can you show some solid evidence of this? WD claims to be fully functional on my 2 Windows 7 boxes running Avast 5 Free.
If Avast 5 is disabling WD its doing it wrong because WD claims its functioning normally. It should not be disabiling WD anyway.
Avast 5 does not have some of the protection WD has.