Something that will help when designing your HUDs is to use normalized screen coordinates rather than pixel coordinates. If you use pixels, you need to account for all the possible resolutions you want to support... no fun.
Instead, choose and origin (say, the bottom left of the screen) and call it <0, 0>. The top left of the screen would be <0, 1> and the top right would be <x, 1>, where x is dependent on the aspect ratio. For example, at 1680x1050 the aspect ratio is 16:10 so x would be 1.6.
Now you can design your UIs in normalized screen coordinates and they won't be stretched/skewed when the aspect ratio changes, and they'll scale perfectly regardless of the resolution. The only adjustments you might have to make are for 3 or 4 aspect rations (4:3, 5:4, 16:10, and 16:9 probably). You can even alleviate that by allowing things to be anchored to the right hand side of the screen.