Which post says that John never used his debit card on his computer? That's the post I missed.
I am sure he did use his card to buy stuff on the internet! As most of us have. The danger in that has nothing to do with how secure your personal computer is, it has to do with how secure the databases full of card numbers at the business you buy from are, how trustworthy ~their~ employees are, and how many people know your card number. Your understanding of how credit card fraud takes place is seriously lacking if your first response is to ~mock~ him for using Internet Explorer. Credit Card theft has nothing to do with a firewall or computer hacking, it has to do with someone getting the card number and using it. It probably has nothing to do with fraud on the part of the business named here. Chances are they were snookered too. The teenager at the gas station I went to yesterday has more access to my card number than someone browsing through my computer has.