IE7/IE8 Compatible rendering floated layout wrong

Question

I have a site with a right sidebar and a left main content area. Code looks like this:

<div class="leftside">leftsidecontent</div>
<div class="leftside">leftsidecontent</div>
<div class="leftside">leftsidecontent</div>
<div class="leftside">leftsidecontent</div>
<div class="rightside">rightsidecontent</div>
<div class="rightside">rightsidecontent</div>
<div class="rightside">rightsidecontent</div>

with

.leftside
{
  float:left;
  width:710px;
}
.rightside
{
  margin-left:720px;
}

(see actual site at http://blog.stephenkiers.com/)

Reason it is coded this way is so that because the leftsidecontent is important and I want to be first data accessed by visually impaired visitors; instead of them having to skip all the fluff every time!

The code works in FF, IE8, Safari etc; but in IE7 the rightside divs clear the floated divs.

I would love any suggestions you may have. I have some ideas about how to fix it; but they all involve pretty big rewrites.

thanks!