Rounded corners

Hi, I?m working on a website for myself. Partly for the sake of learning ASP and eventually for personal gain.
 
For this first run I am basically trying to implement some of the features found here on this site. Looking at the basic layout of the pages here I?m seeing a lot of rounded corners. I have done this using nested div tags and frankly it?s pretty ugly. I mean it looks fine but the code is a hairball.
 
I am wondering how you achieved this effect here. On the home page it appears to be done using div tags. On the forums it appears to be done using tables with background images. That?s just at first ...