Unlike other Alpha PNG fix scripts for IE6, DD_belatedPNG ensure that background-position and background-repeat are properly supported and fixes the grey background issue.

There is no usage of AlphaImageLoader, so script doesn’t have the buggy z-indexing associated with that filter.

IE6 alpha png fix

The script is lightweight, 6.66Kb uncompressed – 3.89Kb compressed and easy to implement:
insert the .js file, create another script node and define the class the fix will be applied to, like this:

<!--[if IE 6]>
<script src="DD_belatedPNG.js"></script>
<script>
  /* EXAMPLE */
  DD_belatedPNG.fix('.png_bg');
  /* string argument can be any CSS selector */
</script>
<![endif]-->