CSS - 800x600 Not Optimized

I have a site that fits all resolutions except the dreaded 800X600. I actually want to page to overflow with a horizontal scrollbar but I've had some problems getting there. Is there a simple way to accomplish this with a fluid design?? Thanks

Site
CSS

I've been making that for a few days now. It used to be larger, but didn't fit on an 800x600 display.

I resized the three sliced BG images down to 641px from 684px. I resized #main to 768px.

I chose 641px for this reason... The left side BG is 125px wide. The border for #main is 2px. 641 + 125 + 2 = 768px

Right? Is my thinking clear?

It all looks great in all 3 major browser, IE, FF, and Opera! I'm stoked!

I have FF, but I did not have that developer extension. So, I downloaded it. This is GREAT!

Now, when I resize to 800x600, the window I had it in shrinks, and I STILL get a horizontal scrollbar. I don't care about a vertical scrollbar. I'm not worried about that, but I don't understand why I get a horizontal scrollbar. Is there some web development piece of info I don't have, or am I just doing something wrong. Now, let me also say that the entire page still actually fits on screen at 800x600, meaning that all text is still visible, and all links/images can be seen, but the fact that there is a scrollbar at all annoys me...

Please have a look-see, and tell me what you think, folks.

All in all, how do I ensure that anyone with any screen can effectively view this site?

Chris

I am curious to know what many of you think about the design consideration for 800 x 600. I am about to start a major project and am considering going to a fixed width of 1024 instead of my current default of 770. As I see it only about 1 of 10 use 800 x 600, and I think that will go down in the not too distant future. I wouln't mind learing how to scale a site so it looks good in any resolution but as I understand it you can not scale images that many of my site layouts depend on. Tom