Just to add, evaluate your surroundings.  Most out-of-the-box monitors are defaulted for office use, very bright for a bright environment.  Proper calibration should be performed in an environment where lighting is consistent.  If your set up is in a darkened room, then maintaining calibration shouldn't be a problem.  However, if lighting is variable and you tend to work at different times of the day, then your display will change dramatically.  Either place your workstation in a controlled environment or pick a time of day when to use Poser.