For future reference here is the final result with pixel perfect precision:
The CSS code:
._25 {
width: 21%;
display:
One answer is Blueprint. I have read where you don't think it's the answer, but it's still the way I would do it. All the ease of tables with all the power of CSS.
With blueprint the math is pretty easy. Let's say your form spans 10 columns.
<div id="contact-form" class="span-10">
<h3>Contact Form</h3>
<form action="contact">
<div id="form-sec-1" class="span-5">
<label>Name</label> <br/>
<input type="text" name="name" /> <br/>
<label>ZIP code</label> <br/>
<input type="text" name="zipcode" />
</div>
<div id="form-sec-2" class="span-5 last">
<label>Email</label> <br/>
<input type="text" name="email" /> <br/>
<label>Country</label> <br/>
<input type="text" name="country" />
</div>
<div id="form-sec-3" class="span-10 last">
<label>Message</label> <br/>
<textarea name="message" />
</div>
<div id="form-sec-4" class="span-8">
<input type="checkbox" name="copy"/>
<label>Send me a copy</label>
</div>
<div id="form-sec-5" class="span-2">
<input type="submit"/>
</div>
</form>
</div>
I think this is what you are looking for:
http://www.alistapart.com/articles/prettyaccessibleforms/
It should help simplify your structure a little bit. It doesn't explicitly describe how to make multiple column forms, but the technique could probably expand to that with some creativity on your part.