Ummm... So are you using Windows and Active Perl?

Personally I never bothered to use custom icons, I think icons are rather distracting, and I always view my files in detailed view.

If you are looking for a program to create custom icons, try the Axialis Icon Workshop (I think this is one of the best commercial product). Or other free alternatives (search with google).

One thought, have you turned off the Hide Extension for Known File Type option in your Explorer?