When I play the video in my 27" iMac the colors look great.
You can't really use that as a benchmark, though. Operating systems, graphics drivers and even playback software all can and do alter the signal. In order to accurately judge the quality of your video, you have to first make sure you're seeing it accurately. That means getting it off the computer and into a properly calibrated TV. Until you do that, you just don't know if there's a problem or not.
