so, don't allow .php, or .php3 files to be uploaded, you can do a simple mime-type check to check for that
if (mime-type check == "mimetypeforphp")
{
//don't allow
}
else
{
allow
}
or you could let them upload .php and .php3 files, but rename them to .html or any other extension, then they won't be interpreted by apache and the webserver