As a computer geek I agree with the poster above... if you have to buy a whole new computer because of bugs and virus' and porn (oh my) then you've been taken. In 20 years of tech I've only lost 2 hard drives to bugs. The good ole Monkey B of 8 years or so did quite a number on re-writing the sectors on a hard drive. Yet the drive itself was NOT physically damaged... boot with a boot disk and reformat and voila.. all better. Well... you've lost all your data, but you should never have to buy a new computer in this scenario.
As far as the original letter writer goes. Unless their computer was effed up from his porn surfing it isn't possible for it to just "pop -up" while trying to watch a DVD. She really had to be looking for it.
If he did infect the computer with his porn surfing he should be apologizing about that more than the actual porn watching itself! I personally charge $100 to clean up and secure a machine after a nasty infection... $200 if I have to re-install the entire system. Another $25 gets you a one on one tutorial for keeping your computer safe. :) Many techs charge much much more... with a new baby in the house that's an expense they really don't need.