Grab Center Column Height And Force Same Size On Left One?

As the title suggests, I want to grab the height of the center column and force my left and right columns to be the same height. The bit of code below is from MyWebTronics, and it's great (awesome job, Jason!)... but it is designed to grab the tallest column (regardless which one it is) and then set all the rest to the that same size.

Code JavaScript:
<script language="javascript" type="text/javascript">
fixHeight=function(){
var divs,contDivs,maxHeight,divHeight,d;
maxHeight=0;
contDivs=[];
divs=document.getElementsByTagName('div');
// get all <div> elements in the document
for(var i=0;i<divs.length;i++){ // for all divs...
if(/"fixheight"/.test(divs[i].className)){
// find those with the class attribute 'fixheight'...
d=divs[i];
contDivs[contDivs.length]=d;
// determine their height, defined as either offsetHeight or pixelHeight
if(d.offsetHeight){ divHeight=d.offsetHeight; }
else if(d.style.pixelHeight){ divHeight=d.style.pixelHeight; }
// Keep track of the largest div height
maxHeight=Math.max(maxHeight,divHeight);
}} // assign all divs the height of the tallest div
for(var i=0;i<contDivs.length;i++){
contDivs[i].style.height=maxHeight + "px";
}} // Run fixheight on page load
window.onload=function(){
if(document.getElementsByTagName){ fixHeight(); }
}// ]]>
</script>

In my case, I always want the center column to define the height for the left & right columns. SO... this means
(1) I need to wrap my center column with <div class="fixheight"></div>.
(2) I need to modify the portion below so that it will write my side columns (wrapped with <div class="sideheight"></div>) to the same height.

Code JavaScript:
// assign all divs the height of the tallest div
for(var i=0;i<contDivs.length;i++){
contDivs[i].style.height=maxHeight + "px";
}
Javascript is not my specialty at all, and I'm hoping to rework this to write the sideheight style instead of fixheight.