If you upgraded to PHP 5.3, chances are high you’re going to run into a few warnings or deprecated function messages.
An example is the ereg family of functions, which are gone for good, as they were slower and felt less familiar than the alternative Perl-compatible preg family.

This script adds near-native PNG support with alpha opacity to IE 5.5 and 6. Now you can have full translucency and no more ugly grey borders! Full CSS background positioning and repeat are supporting (including CSS sprites). It requires only one line in your CSS file, and no changes to your website HTML. <IMG> tags and background images are both supported.