To add to your woes... your layout is fluid, so if the browser window happens to be narrower than your site width, everything gets jammed up. I noticed this because I keep my browser window about 1000px wide, so I can see other things to either side of it.
I wondered, back when you started the thread, why you didn't just combine your two images into one, as wide as you need it. But with a fuild layout, I can see why you didn't do that.
You might try using the min-width setting in CSS. Some browsers ignore it, but some, at least, will obey.
Rob