Is it reasonable to hope that Avast can remove this nuisance from Windows 7/Internet Explorer or is this a job for the new browser cleanup tool and will this clear the nuisance from my system?
I’d suggest to use AdwCleaner. 
Instructions: http://forum.avast.com/index.php?topic=53253.0
Probably not, since technically Conduit isn’t malware.
This is a job for AdwCleaner or Junkware removal tool:
http://www.bleepingcomputer.com/download/junkware-removal-tool/
By the way, you can uninstall it manually, see this:
http://deletemalware.blogspot.com/2012/01/searchconduitcom-uninstall-guide.html
Or you could simply reset your web browser.
Cheers!