We are doing both upgrades later this month. We're installing EMV readers, but are not enabling them yet because it is still in testing phase for our processor. We'll enable it when it's fully supported.
As to why upgrade to Windows 7, you may want to include your IT Dept. in the discussion if your machines are integrated into your network. I understand this has been an audit point in our internal third-party IT audit.
My frustration has been our ATM vendor did not make the software upgrades to support Windows 7/EMV available until last Fall, and our processor only recently started to support it. When I opened the ticket for the upgrades in January, our processor tried to talk me out of the EMV portion due to the pending ruling on the Durbin routing provisions, which may have some impact on the chip.
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Let's start at the very beginning; A very good place to start...