I want to achieve this in CSS - not CSS3 as I want it to be supported by all browsers
ie a div containing content, with the shadows on every side. The top area will be
CSS3pie is a tool that lets you use some css3 properties in IE.
What you're trying to do is fairly widespread css3 in newer browsers, and emulated really well (and easily) in IE with the .htc file you can download from there.
As for the markup, I see just 2 elements, with the top one floated right, for example. You'd have to play with z-index to hide excess shadows. In that site there's also a very similar effect, you should be able to adapt it for your needs.