Perhaps the correct response is some (more) user education and then allow evolution to take over - those people who are too stupid to work this out lose all their money and then they can't use the Internet any more.
I don't buy this line of reasoning any more. Don't open attachments from people you don't know. Don't open attachments from people you do know. Don't open attachments that have innocent looking icons like a text file. Don't preview emails that have attachments. Now we're in an arms race where trying to send any email attachments around the internet is a sure fire way of getting someone to blackhole your entire email for "malicious content"[1]. Even experienced users running around with all the latest antivirus and ad zappers and everything can *still* occasionally get infected with spyware.[2] How do you expect users to keep up? [1]: True story: "Email me the zone file! oh, I'm sorry, we don't accept .com files, .zip files, .doc files, .pdf files or files with .'s anywhere in the name other than the 4th to last charactor, or ones that contain the phrase "smtp"...." [2]: We don't need everyone to post their stories about how they use program X and they haven't had any spyware/viruses/whatever. We know.