[link|http://msdn.microsoft.com/library/default.asp?url=/library/en-us/UxGuide/UXGuide/Windows/DialogBoxes/DialogBoxes.asp|http://msdn.microsof...s/DialogBoxes.asp]
Shrink your window until the image should cause a side-scroll. Note that it doesn't actually offer scroll bars -- at least in IE6 -- meaning if you have a small screen you won't ever see the whole image. I didn't even bother to look at the source for the page, but they obviously aren't using plain old HTML.