A few quick comments looking through the source:

You did very well in structuring things semantically.  I only see a few <br /> or <b> tags.  That said, you probably want to include more semantic markup for some things, e.g.,

    <div id="post">
    	<b>Introduction</b><br />
    	<i>Thursday, January 27, 2011</i>
    </div>
    <br />
    <div id="content">

If I were to rework it, I would do:

    <div id="post">
     <h1>Introduction</h1>
     <h2>Thursday, blah blah</h2>
    </div>
    <div id="content">

Then your CSS will style those elements:
div#post h1 { ... }
div#post h2 { ... }

For your images, unless you need a javascript id selector, I'd probably make them a class, rather than unique ID's.  It looks like your images will all be styled similarly, so why not group them using a class?  Or just override the CSS defaults for the image tag.

Finally, you should probably use a CSS reset.  Browsers all use different defaults, so the only sensible thing is to use a reset so that all styling attributes start out the same across all browsers.  Eric Meyer is the CSS guru, he has his reset at http://meyerweb.com/eric/tools/css/reset/ (along with more explanation about why to use it).