The bad news is that the spyware situation for home pc users can be murkier every day. I remember a particular user who once installed an antivirus program because a popup appeared claiming to have found viruses on his drive, next thing he knew he was having all sorts of spyware problems, viruses found all the time (to “prove” the antivirus component was running.), etc. etc.
Spyware Confidential has the story on the latest wolf in sheeps clothing, something called spyaxe. This link shows a screenshot of one fake warning. One problem is how to describe to people how to identify legitimate versus illegit popups and warnings.