What kglad said.
And Camera Raw 7.3 is only compatible with Photoshop Elements 11.
http://helpx.adobe.com/x-productkb/global/camera-raw-compatible-applic ations.html
If you don't want to upgrade to Elements 11 then your other option is to convert the Raw NEF files to DNG with the free DNG converter. Then edit the DNG files in Elements.
http://www.adobe.com/products/photoshop/extend.displayTab2.html