I just finished assembling my new rig with the Core i7 920 processor and 6 gigs of DDR3 ram.  The 920 at 2.67 mhz is the bottom of line of the 3 new processors (the others being beyond my budget).

I have not had much time to work with Poser yet, but so far it is sweet.  With 6 figures, hair, some clothes, props - it is smooth as silk.  My 2 year old AMD just could not handle a scene with that much stuff.  I seem to have less trouble with 'lost textures.'  May just be a coincidence.

Rendering time on 4 threads is good.  I did not set a stop watch, but I am sure it was under a minute or two.  I think the processor has the ability to work in 8 cores, but Poser is limited to 4.  Don't know if it matters, as 4 threads seems to be enough.

Supposedly the RAM needs to be installed in 3s.  There are three channels (whatever that means.)  As soon as I have an extra $200+ I will add 6 more gig for a total of 12. 

If I learn anything new with more Poser time, I will update.