Most users don't know much about computers and really don't want to know.
To them a PC is a machine just like a car or a microwave if it does something odd then it is broken and should be fixed or thrown away. I've heard of many machines that were thrown away when all that was needed was a reformat.
Most of the machines I've fixed in the last year have problems caused with spyware. The users are usually quite surprised to find out what a nasty place the interweb is. I'm finding I spend at least as long explaining what has happend to their machine as I do fixing it.
The users are not usually thick they just find the workings of a PC a bit abstract. If you use a metaphor they can cope with they will get the idea quite quickly. I often describe using spyware scanners as being a bit like washing your car, the crap builds up over time and mileage and you should give it a clean once a week or so.
It's not accurate and it's overly simplistic but it gets the idea across. Similar silly stories work with AV and updates.
They're not geeks after you speak with them but they are a bit less of a noob.
