I was thinking 'bout it. If i am to make a big php integrated system(like phpBB)... how should i keep my coding structure. Should I embedd it into HTML and then make it or like phpBB does... keeping all PHP files non-GUI and then calling .tpl files.
Keep the (x)HTML out of that php-code. Your php-code will become very unstructered when embedding it in (x)HTML.
Search on the internet and try to find a project where the code is embedded in (x)HTML. Compare it with the code of a project like phpBB. You'll find the code of phpBB much more understandable...