Your most secure way of uploading files in php?

Hi Guys,
I am making a file upload script and actually found this one somewhere and though if it is secure enough, if not how would you make it more secure?

if ($_FILES)
{
$temp_file = $_FILES['ufile']['tmp_name'];
 $upload_dir = "uploads";
$name = $_FILES['ufile']['name'];
switch($_FILES['ufile']['type'])
{
case 'image/jpeg': $ext = 'jpg'; break;
case 'image/gif': $ext = 'gif'; break;
case 'image/png': $ext = 'png'; break;
case 'image/tiff': $ext = 'tif'; break;
default: $ext = ''; break;
}
if ($ext)
{
$n = "$pic_name.$ext";
move_uploaded_file($temp_file, $upload_dir."/". $n);
echo "Uploaded image <img src='uploads/$pic_name.$ext'/> as '$n':<br />";


}
else echo "'$name' is not an accepted image file";
}
else echo "No image has been uploaded";


?>

Code (markup):

And, this would be the HTML form

<form enctype="multipart/form-data" action="upload_photo.php" method="post">
    <input type="hidden" name="MAX_FILE_SIZE" value="1000000" />
    Choose a file to upload: <input name="ufile" type="file" />
    <input type="submit" value="Upload" />
  </form> 

Code (markup):

 

It depends on what you mean by "secure".

I would change:

if($_FILES)

Code (markup):

to

if(!empty($_FILES))

Code (markup):

First of all because the first compares $_FILES to true, which is not the best way.

There also needs to be verification of the image's size.