I used avastclear and it left a lot in the Registry.
Procedure was:
run avastclear (safe mode), after reboot delete Prefetch data (I do this after major changes to save the poor OS from getting confused) and check the directories to delete any left, run RegHelp, reboot, Reghelp again (and each time it finds a lot of Avast entries), install and set up 2006 from scratch, reboot.

Revo does a better job than avastclear does.