First off, if by header and body you refer to the elements with id "htmlheader" and "bodydiv" respectively, there is nothing between them as the "htmlheader" actually contains the "bodydiv". Also, I wasn't talking about moving the register and login links above the htmlheader, just to another place inside the "htmlheader" element, namely in the table that appears at top level in the htmlheader, rather than after this table.
I dont't know what you mean about "margined version", but if you mean that you want that image as background for the register/login links, then by all means, set background-image: url('location/of/image.jpg') for the div that contains the links.