So you ignore the widescreen format alltogether?
Yep. You pretty much have to decide on an aspect ratio and stick with it. That means letterboxing 4:3 to go widescreen or the opposite if you stick with 4:3. Even XBox360 and digital TV has to decide on one or the other and black out areas of the screen or leave users unable to see some areas. Leaving users unable to see certain areas just doesn't work on most types of games.
I've heard a lot of arguments from people who don't fully understand the problem that it's not necessary, but it is if you want to be completely consistent. Anything else and you're either stretching square objects into rectangles or your nicely aligned GUI has gaps in it.
Interesting that you use a medium-res graphics set. So in, say, 1600x1200, you scale the graphics up, but still allow them to be positioned at whole pixel coords?
I'd have to double check, but I think I'm using floating point drawing coordinates.
I'm wondering whether to do a hires bitmap because if I were trying to make it 1600x1200 that's a lot of detail to have to draw.
Yep, another reason I went the mid-resolution route.