upload file size

Hi i really need help with an upload script. right now i use if ($HTTP_POST_FILES['userfile']['size']>$maxsize) { echo "File too big"; exit; } to determine if the file is larger than allowed. but the problem is, that if the file IS larger, it is still first fully uploaded and then checked. i tested it several times - if the file is much larger than allowed, it displays the error message but the page loads a lot longer and my computer is sending the file to the server. this could really kill my bandwidth. is there a way to check the file size without fully uploading the file? thanks joe