Special kind of 3 column layout

[Dean C]

I'm sure this has been asked before, and I did do a search, but sifting through the mass of CSS threads on multi-column layouts proved to be a nightmare.

What i'm looking to do is have a fixed width layout of say 700px width. Then within that I'd have 3 columns. A left column of width 150px, center column of width 400px and a right column of width 150px. However, what I want to be able to do, is that if I decide not to include the div for the left hand column, or the right hand column, or both, then the center column will expand into the space that was once occupied by the other columns.

The thing that makes this slightly easier than other 3 column layouts is that the background colour of all 3 divs is white, so I don't need to stretch any backgrounds All i have to worry about is the width of the columns.

I need to support IE6+, Firefox, Opera.