For the 8 y/o old monitor I was using, Calman Client 3 would annoyingly prompt me about reading DDC every single time it was started or I resumed from sleep, and since the application of the profile doesn't survive a reboot, I began looking into why. I hoped I could get away with using the Windows Control Panel applet, but it doesn't apply profiles the way Client 3 does; at least, I could not get it to apply the LUT and monitor adjustments. While Client 3 behaves perfectly with my new monitor and TV, I do have issues with it when logging on as a different user. It would be great if I could avoid running it except during calibration, but I can't get the Windows applet to do what Client 3 does.
As best I can tell, Windows Color Management supports visual calibration of a monitor and can record and later apply the changes one makes through it. It also supports central management of ICM profiles, including the ones Calman creates, and software that is color management-aware can query Windows for the profiles and use them. However, the Windows applet apparently cannot apply the LUT and monitor adjustments contained in those Calman ICM profiles, which makes it pretty much useless to me.