how to make sure background streches horizontal?

[tagknife]

here is my websitehttp://albuquerqueautomotiveservice.com/but i coded it in my old computer and its monitor is rather squared then widescreeni just noticed in my laptop the right side of the page is gray how can i make sure it stretches only horizontally?thanks\[code\] body { background:#333 url(bg.jpg) no-repeat; width: 100%; font-family:Arial; cursor: url(images/wrench.cur); }\[/code\]