Color Banding, ugly gradients, gui elements off

Hey folks.

I have 7.1 iMac at work. (aluminum, )
2GB ram.
2.4Ghz C2D.
256MB video (ATI Radeon HD 2600 Pro)

At home I have a 5.1 iMac (white plastic chin, a year old)
2GB ram.
2.3Ghz C2D.
256MB video (I dont remember the card)

Working at home, the graphics looks a lot better. There is less banding when dealing with subtle gradients. At work, there is lots of banding, and even gui elements seem wrong. Take a look at the attached. Zoom in real close. You can see a box around each button!

I have both using 'Millions' of colors. Both running 10.5.1.

What could be giving me poor color at work but not at home? Being that I can show you the incorrect color in a screen shot... I am thinking the video card is working fine and it's Leopard not working right. Any thoughts?

Thanks in advance,
Jules

Well it can't be the monitor if you can capture this in a screen shot, but yes, it could be the card. If the card is not rendering colors correctly, then it would affect any output. It could also be Leopard (wrong drivers?). Have you tried adjusting your contrast and brightness settings? If one or the other is set to an extreme, I suppose that could be part of the problem.

Yes I've adjusted brightness/contrast, I set up a few calibrated profiles. It doesn't do anything. Changing brightness & contrast does not change the number of colors the card/monitor uses.