Oh, so you went ahead and it full screen. That was quick! I thought you would have more problems with the radical shape change. I guess since the game display scales in and out, you can keep the sides from extending out too far fairly easily in all cases.
I assume you'll be supporting both 16:10 and 16:9. I actually use a small HDTV as a monitor (16:9). 1366x768 native res on the panel, with 1360x768 PC resolution (multiples of 8, drops 3 pixels on each side). These are becoming fairly common, and they all seem to support "VGA" input anymore. This is also one resolution a lot of Xbox 360 owners clamored for, in order to get native res on their HDTVs through the 360's VGA cable.