Arrgh. Having just dealt with yet another PC which had a preloaded 90-day trial AV when they bought it - three years ago -, I had to vent. DELL, HP/COMPAQ, SONY, pretty much everybody who does this, I hate you. You both suck and blow. Like Megamaid. Go watch SpaceBalls.
I doubt that 3 in 10 people actually go buy the AV package (assuming they understand that the need to in the first place) and the response is almost always the same: "Yeah, I have a virus program", (I bite my tongue on the obvious response...).
*sigh* I guess it keeps the shops busy, but I still occasionally ponder if perhaps the conspiracy theorists aren't right and the AV vendors do some moonlighting as virus writers.