I agree with Saurav Cheeta! PHP+MySQL based dynamic sites can't be downloaded like that! They keep changing every now and then. Everytime some visits a page, that page first gets "generated" from the code and then it is handed over to browser for display.
And even if you start downloading every page that gets generated, do you realised how many pages will there be? How much time it will take? How much bandwidth it will consume?
And most importantly, by the time you finish downloading, things would have changed.