Question on PhP, MySQL

Question on PhP, MySQL

I am thinking of a consumer internet business for which I will have to
build a database driven site.

I am thinking of using
PhP, MySQL as the main technologies amd Linux hosting( and some
Dreamweaver).

My question is:
what is the maximum number of hits (UUs) a day/month can such a site
with these technologies handle ?

How robust is PhP, MySQL?

Thanks

Kim