HA!!! I can't believe I didn't see this before...
You've got it working just fine... the only thing you're doing wrong is your div statements.
Change and to and and you should be golden. Oh, and ya, change the rightbox definition's float to right instead of left.
I did some testing of my own and with the following CSS:
#wrap {
width: 1024px;
margin: 0 auto;
}
#leftbox {
width: 678px;
float: left;
}
#rightbox {
width: 346px;
float: right;
}
and the following HTML
<body>
<div id="wrap">
<div id="leftbox">
Featured Content
</div>
<div id="rightbox">
Recent Threads
</div>
</div>
</body>
I get a 2-column effect as intended but if I used "