@evildictaitor:Unless your POS is written in Java, how many POS client would have Java installed?
More importantly, I've not seen any announcement from Oracle that they're going to release JRE for WinRT. So this would be non-issue at least for now.
@cheong: The WindowsRT restrictions have nothing to do with ARM being inherently more secure than x86. They are due to the OS having a more restrictive policy. It is entirely possible to run Java on ARM. It's also possible to buffer overflow ARM devices, and to exploit sandbox logic bugs such as those in Java and .NET.
Running on ARM doesn't afford you protection. Running on RT does.