I guess the feel must be better, since you have a spare CPU doing almost nothing, but didn't anyone do some benchmarking to see if this changes anything in render times?
I use dedicated computers with a stripped-down Windows for Poser, nothing else is running on them, so the spare processor is of no use if it doesn't help reduce rendering times any.

Praying for a 64-bit, multiprocessor-aware version of Poser