I got it by putting together many different sources. Alex Coles' solution was closest right off the bat but the middle wasn't centered. It was much cleaner than my mess too. I started with the code from this post:
<style type="text/css">
.leftit {
float: left;
}
.rightit {
float: right;
}
.centerit {
width: 30%;
margin-right: auto;
margin-left: auto;
text-align: center;
}
.centerpage {
width: 80%;
margin-right: auto;
margin-left: auto;
}
</style>
</head>
<body>
<div class="centerpage">
<div class="leftit">Hello Left</div>
<div class="rightit">Hello Right</div>
<div class="centerit">Hello Middle</div>
</div>
(fiddle for above)
I took the elements Alex cleaned up which got me even closer to my goal, but the center color blocks were way too wide. From this question I learned about "max-width", which ended up being the final piece I needed...or so I thought.
Edit: max-width doesn't work in IE7 quirks mode (which I have to support) so from this page I learned how to tweak my css to work in IE7 quirks mode, IE8, and FF.
The final code (fiddle):
.leftit {
float: left;
font-size: 0.8em;
}
.rightit {
float: right;
font-size: 0.8em;
}
.centerit {
width:220px;
margin-right: auto;
margin-left: auto;
font-size: 0.8em;
}
#headmiddle div {
border: 1px solid #000;
margin-bottom: 3px;
}
.centerpage {
margin-right: auto;
margin-left: auto;
text-align: center;
}
strong { font-weight: bold; }
.search { background: orange; }
.active { background: #8ed200; }
dt { float: left; font-weight: bold; }
dd { margin-left: 4.5em; }
<div class="centerpage">
<div class="leftit">a little search form here</div>
<div class="rightit">
<dl>
<dt>Legend:</dt>
<dd>Status numero uno</dd>
<dd>Status two</dd>
</dl>
</div>
<div class="centerit" id="headmiddle">
<div class="active"><strong>Status:</strong>
Active</div>
<div class="search">Search results displayed</div>
</div>
</div>
Thanks to all the great answers - I learned a lot from this question.
Paul