2 column layout where one splits into two.

i want it like this:

__________________|__________
________|_________|__________

i have a regular 3 column layout. not using float right but widths and margins and it works good on all browsers until i added in two more divs to wrap the left and right side. now in ie6 the right column is invisible and i dont know why.
any other way to do this?
this is just the html.

[CODE]<div id=”maincontainer”>

<div id=”topsection”><div class=”innertube”><h1>CSS Fixed Layout #3.2- (Fixed-Fixed-Fixed)</h1></div></div>

<div>

<div id=”contentwrapper”>
<div id=”contentcolumn”>
<div class=”innertube”><b>Content Column: <em>Fixed</em></b> <script type=”text/javascript”>filltext(45)</script></div>
</div>
</div>

<div id=”leftcolumn”>
<div class=”innertube”><b>Left Column: <em>180px</em></b> <script type=”text/javascript”>filltext(20)</script></div>

</div>
</div>
<div>

<div id=”rightcolumn”>
<div class=”innertube”><b>Right Column: <em>190px</em></b> <script type=”text/javascript”>filltext(15)</script></div>
</div>
</div>[/CODE]

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