no... most the browser mal-ware tools out there are worse than the stuff they say they remove.
if you don't want Avast fine... people on this forum have tried lots of different programs and can give you other options.
I personaly use spybot for mal-ware scans because it doesn't have an issue with Avast and the two programs get on... DON'T have more than one anti-virus program installed on any system at the same time.
Run your scan then remove the anti-virus program and install a different one if you want to but remove the first one before adding another and don't allow something to use your web browser to scan your system... it never ends well.