Why on earth would you argue this issue with the guy at the paint counter? He clearly has nothing to do with either the cause or any remedy they might decide to offer.
The interesting part to me was it sounded like the managers explained to them that it was all the bank's fault. Not that Home Depot was too cheap and lazy to update their software. And ya got to talk about something while the paint's shakin
edit: Also, keep in mind that some retailers are running POSReady 2009 / POSReady 7, which may look just like Windows XP at first glance.