Are any of you aware of software/hardware for charging credit cards that is available for Windows devices? I'm looking for something like Square or ems+ that will work on either my Nokia 920 or my SP2. I do event photography for Halloween and Christmas so I have pretty low volume and I don't want any monthly fees. I have Square that I use on my old iPhone 4 but since I accidently upgraded it to iOS 7, it is painfully slow and the square app is practically unusable. Thanks!