RAW files from a camera that is too new to be supported directly with CS3's version of ACR can be first converted to DNG using the latest free DNG Converter available from Adobe, and then can be viewed in Bridge and ACR even though the original RAWs cannot.
Your student's RAW files should be convertible in the latest version of Canon's Digital Photo Professional as well, which should have come on a CD with the camera as well as downloadable from Canon's website.
Additionally, make sure you are running the latest Camera RAW for CS3, which I believe is ACR 4.6, available from Adobe's website.
Just to make sure that is the issue, what Canon DSLR model is your student using that Photoshop does not recognize the RAWs from?
Thank you I installed the newest version of ACR useable with CS3 and the DNG converter. That did it!
Thank you for your help! It worked. Now I just need to install on all
the rest of the lab.