Right, I see what you mean now. My monitor is 19", so the background fits just perfectly in my browser. But I adjusted my resolution and yes, that is a big of an eyesore.
You want the flag to run down both sides of the browser, correct?
This can be done, but I don't know well it would work. It will also be a bit tough. Take a look at this thread...
http://www.thescripts.com/forum/thread97767.htmlAs you can see, this is possible with CSS, but it's not the easiest thing in the world. After I get some rest, perhaps I can take a crack at it and come up with something that might work. Hopefully by then, someone will have come along with an easier solution.
EDIT: There ya go, someone already came up with something else while I was typing! You'll definitely want to give Michael's suggestion a try before attempting something as complicated as what I linked to.