The malware report here says they analyze protection from "malware downloads". If so wouldn't that be the job of an antivirus program? I don't understand why the browser is supposed to do this.

If this is basically duplicating what antivirus programs do anyway, then has IE just added some GUI integration with MS's antivirus, and that gives it the good result it gets here? It seems like all browsers will be equally safe given the same antivirus installed on their machine, so the result seems meaningless.

Even less clear is the other report, on click fraud. It mentions software running on the client's machine ("click fraud software installation" etc.), so basically we are again talking about malware? And again, wouldn't a program separate from a browser - an antivirus program - be the right tool to handle that?

Lists of dangerous URLs are something that browsers can do that antivirus programs can't. But oddly that is not the focus of these reports.