If you need the four images to be backgrounds, you may use
<img src="imgname.gif" alt="" style="position: absolute; left: 0px; top: 0px; z-index: 1">
... and so forth for each image.
And for the body tag, use
<body style="z-index: 2">
What this does is it places the 4 images at the four corners (or where ever else you need them). z-index of body being higher, the text in the body will display on top of the images, making it look like a background.
MOVING THE TEXT TO THE MIDDLE
Thats a tricky question. "style: left: auto; right: auto" should work, but it doesn't in some browsers (read "IE")
Doing a "text-align: center" in IE incorrectly centers block level elements. Mozilla correctly centers inline elements. So basically, you need a workaround that tricks IE into using "text-align: center", while retains correct "style: left: auto; right: auto" for standards compliant browsers. I am not a pro at this, so don't take my word for it
Stefan, waiting for your reply