The latest version of ACR that is supported by PS CS3 is version 4.x.
Support for the Canon 5D II was introduced in ACR 5.2
Support for the Sony A850 was introduced in ACR 5.6
Options a. Use the latest DNG converter available from Adobe for free and convert the raw files to the DNG format. This will allow ACR 4.x to view the files and process them.
b. Upgrade your software to a later version PS CC (subscription photographers package) which will allow you to use the latest technology available from Adobe to process the raw data or PS Elements 12.
c. Purchase the latest version of Lightroom which will allow you to use the latest tewchnology available to process the raw files without the need of the DNG option. (you can then continue to use PS CS5 for more advanced editing not available in Lightroom.
See the link below for the list of Cameras supported in ACR and Lightroom http://helpx.adobe.com/creative-suite/kb/camera-raw-plug-supported-cameras.html