ATM's running windows!?!
If it didn't come from such a reliable source I wouldn't believe it. I mean ANY computer that runs windows and is connected to an IP network is vulnerable to mass worms. The old OS/2 system is also technically vulnerable, but seeing as only 4 furry-toothed old geeks still know how to make anything work on OS/2 it isn't such a big drama. Upgrade the systems? By all means. Install windows on them? No, I said UPGRADE.