file upload (permission problem)

Hi, As I know, the uploaded file in php is stored in /tmp directory, then we have to write a script to copy it into the destinations. such as if (!copy($userfile, "/home/pictue/$userfile_name")). Now, I am having a permission problem, It is not allow to copy the file into specific destinations because of permission is not allowed to do so. Security Questions: My web server is running as user (nobody) and group (nobody). So what user and group should I set for the specific destinations. If I set the destination directory to use nobody and group nobody, what security risk do I have to concern (assume the origional is root). Thank you so much for your help Mark