I've used the Gamma utility. The thing I like about the color manager and the profile creation utilities that I mentioned is that when everything is complete one's whole system can be coordinated, and not just one's Adobe programs. Though I'm not sure how far Photoshop takes the output of the Gamma utility, I doubt that it applies it system-wide. In other words, other programs, like the Windows picture and fax viewer for instance (and UltraFractal for that matter), would not necessarily operate under the same harware color profiles and consequently the same internal color-space.