Hi,
I've been using Avast for approx 2 years now. I have used it on 98, 98SE, WinXP, and WinME. I troubleshoot peoples computers and suggest to them to download the home version and we register under their name. I always set the scanners to the highest possible level (including check for removable).
So far, my version has never, ever failed me or caused issues. Occasionally another machine might hang with the virus scanner running at shut down, but with a little tweaking, that is solved.
I've probably installed Avast on approx 20 machines over the last 2 years and not one of the people that I've suggested it to, have complained.
Hope this helps.
Mandy in Australia.
PS Don't worry, I don't sell it - just can't help telling everyone about the wonderful free scanner - hate to see people getting ripped off. Most of my customers are from the lower income bracket.