I just read your post and fired up the new dgIII for the new orbiter build.
I have an Athlon xp3200, 1024mB, GeForce6800U, Drivers 61.77, 256mB, Sony 19" LCD.
I am running at 2048x1024, 32bpp.
Mini-HUD shows flawlessly. This combo works very nice, avg frames = 100 +/-
Might be some ATI driver glitch. Maybe try different, older drivers.