Having a page update automatically when a selection is made inside a <select> tag in a form?

Hello all.

We are trying to create a page that has three <select> tag areas, the
third selection is limited by the second selection and the second
selection is limited by the first selection. As it stands now, someone
could make an invalid selection in the second and third selections because
the invalid options are still available. Is there a way to have a page
reload after a selection is made in a <select> tag area automatically? I
know I could put a <submit> button to have one manually recycle the page,
but we are trying to avoid that. I also know, that PHP may not be the way
we want to go for this. I have written some PHP code, but am far from an
expert. Also, if Java or some other language is the way to go, I can
pursue it. I was just hoping to stick to one language for the entire
application. (I can dream can't I?) :)

Thanks all, I appreciate your input!

Dan