Design for Large OO poject

Hello guys, I've started large long-term project, i'm buildingd my own CMS (content manegment system) with few more developers, compared to nuke i want it to be fully object-oriented, so that adding more modules would be easy and logical, i have built first beta version of it, i want to maximize code reuse, so here is the structure of my classes class DB{} class Member extends DB() class News extends Member{} class Poll extends News{} ........................... All new blocks and modules are added in this place ........................... class NewBlock extends BitOlderBlock{} after this comes the class that's always in the end class Blocks extends NewBlock{} then i have a file that uses all this library looks like this: --------------- <? include ("blocks.php"); class mainPage extends Blocks{ function displayMainPage(){ $this->heading(); $this->block_news(); $this->footer(); } } $page = new mainPage; $page->displayMainPage(); ?> -------------- I'm very new for big Object-oriented projects, but i'm not new to PHP, i was wondering if my design is good or bad, if you could show me what's wrong with it i'd be very thankful Thank You very much, and have a nice day :-) -- Best regards, Daniel mailto:gatop@hot.ee