First off: Please post Camera Raw related questions in the Camera Raw Forum.
Secondly: The free DNG Converter is supposed to be able to work with the same raw formats as the most recent version of ACR for the most recent version of Photoshop.
Camera Raw 7.3 was the first version to fully support the Nikon D600
Camera Raw 7+ requires Photoshop CS6+
You must either upgrade to Photoshop CS6 (to open and edit your Raw files) or convert your D600 files to DNG with the free Adobe DNG converter and edit the DNGs