array sort help

need some help with a script to sort images for a gallery.
I have the thumbnails in a dir and need to display them in the order that you would see them in windows.

here is my code:

'gets all thubnails from the dir'

$dirtoopen="artist/".$galName;
$tn=0;
if ($handle = opendir($dirtoopen)) {

while (false !== ($file = readdir($handle))) {
if ($file != "." && $file != "..") {
$tn++;
$tNF[$tn]=$file;
}
}
closedir($handle);

The order that they are retrieved in is not the same order that I view them in ftp or within windows. I have added sort($tNF); after the closedir($handle); but the orde3r still isn't right. With the sort it displayes numbers (070706a) then jumps to letters (Untitled-03-09-2007) then underscores (_63) and finally back to letters (a15 ) here is a list of how it is outputing the sorted array.

3d1, 3d2, 3d3small, 3d4, Untitled-111, Untitled-1a, Untitled-1b, Untitled-1f, Untitled-1nnn , Untitled-38-copya, Untitled-38, Untitled-4-copya-redo, Untitled-51, Untitled-52, Untitled-54, Untitled-55, art5a, art7, cs5, ff02, ff03, ff04, ff05, ff06, hane-1, k1, k2

Please help me figure out how to sort them (_,00-99,aA-zZ)

This is what is currently outputing:

Untitled-05,
Untitled-1cs3a-better,
Untitled-38,
Untitled-41,
_6A,
art12-copy,
cs4,
fractal-apple,
hane-1,
objects

And this is what it should be:

_6A,
art12-copy,
cs4,
fractal-apple,
hane-1,
objects,
Untitled-1cs3a-better,
Untitled-05,
Untitled-38,
Untitled-41,

 

natsort($tNF);

PHP:

 

natsort($tNF) outputs

(broken link)-should be 'Untitled-05'
Untitled-41
objects
art12-copy
fractal-apple
Untitled-1cs3a-better
cs4
hane-1
Untitled-38
_6A

 

does anyone know how to use the usort function? I think that might work but I have no idea how to create the user defined comparison.