There is actually a fairly simple solution to placing content over the backgrounds. I’ve produced this and tested it in the following browsers successfully:
PC: ie6, ie7, FF3, Opera, Chrome
MAC: ff, safari
Basically you add another div to the page and set it to position absolute, set it’s width and height to 100% and reset the co-ordinates to 0,0. This re-creates the body so that any html there in uses the top left corner of the browser window as an anchor. Place your content in this div and you’re set. In the screen shot below the white represents a div of content that is centered in the middle of the page.