What the heck is going on?

I have got my website looking perfect just the way I want it. open it in firefox and Im a happy man…Open it in IE7 and the whole thing looks like its gone for an acid trip. And I dont understand why. So far Im thinking that it is a problem with the way I have laid out the background image in the body part of the css… but I have done that the same way I normally do and it normally works fine. Could some one please take a look at the coding/site and give me some advice because there is not much point it putting a website up if only Firefox users can see it.
heres the link:
http://www.arctosdesign.com/layout/main.html