The date shows up fine in IE7, just not IE6 (which is what most people mean by 'not working in IE' these days anyway *grin*). That whole section acts differently in every browser though.
The first thing I see is that you are trying to float divs inside a P tag, which is never that great of an idea:
I would first turn meta into a div. Then instead of using a single div to float the date left, use one for the left data, and one for the right, clearing after them. Something like this:
<div style="width:49%; float: left;">
(post date code)
<div style="width: 49%; float: right;">
(posted by, leave a comment, etc..)
<div style="clear:both;"><!-- --></div>
(categories and trackback links here)
</div> <!-- end of meta -->
As for the size of the first letter of the post, you are doing this:
<font color="#996600"><em><font face="Comic"><font size="6">A</font></font></em></font>
CSS would handle this much better. Example:
<span style="color: #996600; font-style: italic; font-size: 180%;">A</span>ccording
Of course you could move that to a custom class within your CSS file, and just apply it like this:
That should help take care of the line height issues as well. If not, you could experiment with the line-height property of that class.