I know it doesn't quite work this way due to the different types of lights (Infinite, Point, etc), but I've found that with corrected gamma, if the total light intensities add up to over 100%, the resulting render will be washed out. The exception to this rule is IBL lighting, in which case the image used will affect the actual brightness of the light.

However, it was covered in bagginsbill's gamma correction thread that the style of lighting most artists use in Poser is way too bright, and they're only using such bright lights because the gamma in Poser is way too low by default. So instead of using proper lighting and correcting the gamma (because Poser 1-7 doesn't provide that option in the Render settings), they simply increase the light intensity, which doesn't produce realistic results. Try using more realistic lighting in combination with corrected gamma. You will be very impressed by the result. Though the second image you posted is a bit too bright, the shading is much more realistic than in the first image.