Simple idea for ERP - please help

Heloo I'm starting project.First stage is for my school work, but i want to develop it to the end. I want to create a ERP based on php for small company's I want to use as many as possible created opensource applications. First i need to choose some framework, maybye someone think that php is not a good idea..I'm waiting for propositions:) I need to add to this framework some graphic database manager. If it possible for all databases, but I did't found any ..I want to start with postgres and mysql., maybye firebird. Second I have to add soe functionality witch is needed for company worker, mayby webmail,small cms for documents... I also need to add sometching for making automatic documentation.(phpdocumentor ?) Thats the first stage.I need it in the short time :( Second i will be developing modules for all departments in small and medium company. More details on the webpage(i'm designing it ) and next posts.. Anyone please help in the first stage...I really don't have much time. Morty...