If your not gona add anthing behind to allow it to "flex", you could use this code.
<img src="http://www.vatortrader.com/forums/site_images/Singapore_Skyline_Panorama1.jpg" alt="" width="100%" height="200" />
This is what it will look like
http://www.eternalshadows.com/vatortrader.phpbut make sure you keep the image below 800 px wide like you have it or when viewing in 800 resolution you'll have to scroll still.