Getting a swf animation to fill the browser regardless of window size

I'm trying to create a page layout that will show my main 1000px wide by 700px high swf centered horizontally, with 500px wide swfs on either side. I want the side swfs to be cropped by the browser window size. That is, I don't want a horizontal scroll bar. The side swfs are going to be animated background patterns, and I'm just using them to spruce up the space not occupied by my main swf.

I got close using tables and an overflow:hidden property, but I couldn't get the table to be centered in the brower. It always left justified and cropped only the right side.

I've used Dreamweaver before, but I'm just starting to learn CSS. I tried putting the swfs in a container div with width:100%, but my swfs wrapped within it and stacked vertically. I tried floating the side swfs, but it didn't work...possibly because floating is still unfamiliar to me.

Maybe I need a center div with width:1000px, and side divs with width:auto and overflow:hidden, all in a container div with width:100%

If anyone has done a layout like this before and can nudge me in the right direction, that'd be super groovy.

nope, didn't work. Tried a bunch of float & overflow combinations. Specifying and not specifying widths. No luck. Thought of putting both sidebars in one 2000px wide div absolutely positioned under the main div, but I can't figure out how to center the divs when they're AP.

Anyone got any ideas?

okay, got it to work using negative margins.

Could you post the lines of your code that allows you to do that? I want to understand better what you did.