You need to set your monitor to "standard aspect" or "4:3 aspect" when you play AH.
There are potentially two ways to do this: hardware and software.
The hardware method is done in the monitor itself. Some monitors (such as the Acer P241) provide three aspect settings: "Standard" which is 4:3 (1600x1200, 1280x960, etc), "Widescreen" which is 16:9 (1920x1200, 1700x960, etc), and "Aspect" which automatically senses the resolution of the game you are playing and sets the aspect to either standard or widescreen accordingly.
The software method is done in your video card's device driver. You set it just like you set up the other graphics settings (anti-aliasing, etc). I can't give you more details than that as I don't recall (I use the hardware method).
When you play AH on a widescreen monitor, you will have "black bars" on the sides of the screen. That is because it is not using the entire width of the display.
As stated earlier though, HT will be supporting widescreen soon anyway so this is a temporary arrangement.
Hope that helps.
-hb
