Vertically Centered and Stretchable page with non-tilable background?

[scooby77]

I'm trying to construct a website which uses a non-tilable background, is horizontally and vertically centered and should be stretchable.

This seems like a fairly trivial task but it is giving me problems.

I have split the page into 3 sections: header, body and footer.

The problem is that the body should be able to fill the entire page, overlapping the header and footer slices.

I am able to make it almost work by offsetting the body to the top of the header, but extra space is rendered below the body. It appears that the browser is calculating the total height of all 3 sections without accounting for the offset and it also seems that the content will not overlap the footer.

Here is the demo I'm working on..
http://cnff.iwireweb.com/test.php

I'm also not very happy with having to use a sliced background in a layer. It means that the page scrolls horizontally when it should just have hidden overflow.

I hope I've made myself clear.
Any help would be greatly appreciated.