Thanks for the post, I've been trying to do the same. I have a few questions for you:
1. The drivers for the control panel (brightness), which ones did you install? I have the bootcamp drivers, but am not sure which .exe to run. Can you post more details about this process?
2. Are you able to get the monitor to work during post? When I turn my computer on, the monitor doesn't show anything until windows has finished loading. My guess is that this is because the LED Cinema Display doesn't support 640x480. Do you have this working, if so then my theory is wrong. Like you, I'm also using an Atlona adaptor, I'm using the one with the USB power, I guess this is their 2nd generation.
3. In device manager, I've noticed that Display iSight appears twice. The first one looks good, but the 2nd one has a 'no driver' warning. I can't figure out which driver it wants. It shows up under 'Other Devices'. I've been ignoring it as the camera seems to work fine with Skype anyways. Do you see the same? In my case, I'm running Win7, so things may be a little different here.
Thanks in advance for your time and help!