PS I would add a green bg color with your background so people with larger monitors don’t see your white space~ :)
Soh Tanaka is right, your horizontal scrollbar is caused by the 1024px width. I just used that figure because that is the size of your bg image. I’m on a 1920 monitor and have no problems. You can set that #container width to 970px without losing your gradient.
I made the body bg white because I thought that was the look you were going for, if not just change it to #139981.
For the nav, take a 1px slice of that bar, set the div#nav height to 30px and repeat the slice along the x axis.