Div and CSS

So I am attempting the no tables all DIV and CSS implementation. Question about the layout structure of DIV’s;

For DIV’s to render properly does it matter how I lay them out in HTML If I am position them all via CSS?

The reason I ask this is:
I am attempting a 3 column layout with a main DIV and then 3 DIVS within. I have played with the layout of how the DIV’s are set up in code view and it changes when placed in different orders even though all are set via CSS.

Also the reason I ask is before I was using all position: absolute; but then found that if my left content area or right content area was greater then main area it would overlap the main content div. Since then I have used float: left / right and things are formatting correctly however I had to change the DIV structure HTML struct.

Whats the deal? Insight much appreciated.

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