to recognize the mark iii raw files I mean.
No deal. You need to upgrade your software. MK III files require ACR 7.1 and that only is available in PS CS6 or LR 4.1.
Or you can download the 7.1 version of the DNG converter and convert your raw files to digital negative. Then you can open those files with what you already have. Another possibility would be to just get Lightroom 4.1. Lightroom does not use the ACR plug-in; all that technology is part of the Lightroom program. Then you could just use the Photoshop you have along with Lightroom.