A recent survey compiled in the UK showed that the common computer user didn't understand, or even worse, had never heard of many typical technological jargon terms.
According to the survey, only 39 percent of users knew what a Trojan was, 10 percent thought spyware was a computer program to check on cheating partners and 16 percent had never even heard of spam.
I would assume if you gave a simple definition test to people in America, you would find similar results. While I don't think it's necessary for home users to know everything about computers, it would be favorable for them to at least understand how to take action against really bad things.
Check out the link above to find simple definitions on some of the more heinous types of computer problems for home users.