29 inch monitor here on Google Chrome (latest) in Windows 7 and no problems here. Looks great having all of that extra screen space with that background.
Thanks for taking a screenshot; I'm only on a 1680x1050 22", so I really have no good way of testing large resolutions! :) What's your resolution? Is it any better now, care to take a new screenshot? (Proxy debugging/designing through HN ftw)
You can create a virtual machine with arbitrarily large resolutions (VMWare supports it) and test there - The vm's screen will be rendered into a window with scroll bars.