I don't think learning Visual Basic is a good base for learning PHP. It is very different, very very different. I'm learning VB myself at the moment, and it's really nothing like PHP or C/++. The latter on the other hand, is a great way to get familiar with coding (if your itention is to learn PHP).
But the bottom line is, if you want to learn PHP, you really don't need to learn other languages on the way. It will be a waste of them and you will possibly get confused with the languages. Now that I'm used to code in PHP I can't stop putting $ before variables in C.

Just like I constantly use single quotes in VB or == in comparisons.