Version 1

The only "problem" with this is that IE scrolls the background (like it should given the default value is scroll) whereas the other browsers set a fixed background. You can set background-attachment to fixed and it works fine in IE6, however IE7 won't display the image at all. Funnily enough, despite Opera showing it fixed by default, if you set background-attachment to fixed the image doesn't display...

If you really care about every browser being the exact same (because you know how many people will be comparing your site in different browsers to picking on tiny differences ) then I present to you version 2:

Version 2

The difference simple being the background is placed on a div which wraps all the content, rather than the scrollable div itself. It should make no difference considering the only difference between the divs is one is overflow:auto, however theory is wonderfully wrong, as per usual. Tested in IE6, IE7, FF3 + Opera 9.

The #1 rule in web development - there is always a workaround