uploads

Hello again; can someone point me to a system for cleaning uploaded files; embedded php scripts in image files, viruses etc, shell escape chars, anything that would be hazardous? The idea is when a file is uploaded, as soon as it gets to the server it is inspected, cleaned/rejected before it is used or sent anywhere else on the server. I am using php to upload anything that would be sent in an e-mail attachment. Once the files have been 'sanitized' they would be made available for display. Thanks in advance; Jeff k