I ran into a small problem at work today. Well, I didn't really create it, but I have to fix it.
So for all people out there designing webpages, read the following.

If you design pages to be viewed on 800x600 resolution, you don't want to make the page (or the flash for that matter) 800x600 pixels. Always take a margin for the scrollbars, the menu, the statusbar, ...
For example, take a witdh of 760 pixels, that should be enough on a screen of 800 pixels to view your site + the scrollbars without having a horizontal scrollbar.

The same goes for sites designed on 1024x768 resolution, they also have scrollbars.
Anyways, try to make it, then set your own resolution on 800x600 and view it. That's the only way to be sure.