Working with designers...

Hi There, I'm looking for some community feedback on being a coder working with designers. Techniques that work that allow my php-inept page/graphic designer comrade make changes to the layout of the page without destroying my code, or requiring me to make any changes whatsoever. Or what is the best process? Code the dynamicity (heh -- sad thing is you know what i mean by it) of the site, then integrate a designers HTML into your code, *or* the other way around.. have the designer create the site using all static html files, then go in and remove sample data to be replaced with dynamic data (pulled from a DB, for example). I'm about to enter a very large project working with about 3 or 4 designers and 2 other coders and any suggestions on making this relationship work is greatly appreciated. Mike