guess its my turn to say something :)
i have now php :) but completely no time to start making use of it. :( And no time to update my site and add up the info i was planning to place. :( Busy, busy, busy!

Anyway: Talking about websites with interchangable layout by means of different cascading style sheets, the following link might be of interest to people wandering what can be achieved by just using a different CSS on the same HTML file:
http://www.csszengarden.com/
Check it out guys, you'll like it (i can give you a "money-back guarantee":) )

About the "php-based png transparency solution": this is nothing but server-side translation of the client-side javascript solution: you just detect the browser and if IE you add up a line using the IE's alpha transparency filter everywhere a png file is included. Don't say its a bad solution: of course solutions based on server-side scripting are always preferable to client-side ones since the later can be disactivated by the user... BUT, when using free hosting one most often cannot make use of server-side scripting, so this has also its disadvantages (just like everything else).