After trying a lot of profiles made by posters I never found a good one that worked for me. Some of them turned grey to green and some where to blueish... I think this one have good color reproduction and contrast. Try this one if you didn't already find a good profile for your 20" iMac. If it doesn't appear in the profiles by the usual way, open ColorSync, Devices, Displays, iMac, Current Profile (click button on the right and search for it). Please feel free to say what you think about it. Cheers.