CSS floating columns problem in IE8

i’m having a problem. if you look at these pages in IE8 (not sure of other IE versions)

http://www.domainanimal.com/domain-name-sales-and-marketing/for-businesses/

http://www.domainanimal.com/domain-name-sales-and-marketing/for-domain-investors/

you can see the right column gets dropped down below the left column, and i cant figure out how to correct it. the code looks like:

HMTL =

<div id="left">
left column content here
</div>
<div> id="right">
right column content here
</div>

CSS =

#left {
	float:left;
        width:525px;
        padding:1em;
}

#right {
        margin-left:580px;
        padding:1em;
}