Attached Link: http://www.thebest3d.com/poser/

Poser 5 is still a very viable program. You can get it at the above link for $50.00 USD.

Many people are still complaining about the bugs in Poser 7, so if you want to upgrade, I would suggest going to either Poser 5 or Poser 6.  While Poser 6  has it's quirks, none are major. 

Poser 6 does lights so much better than Poser 5, but to me Poser 5 is a more stable program.

Poser 6 also has some nifty nodes in the material room that Poser 5 doesn't have.

I don't have Poser 7, but from what I understand it's lights are somewhat more different than Poser 6 (I've seen lights in the MP that only work with Poser 7 for whatever reason), and it has multiple undo (which uses up loads of memory), and it has a morph putty tool which from what I understand allows you to do morphs using your mouse instead of having to turn dials all the time. There are probably other features, but those are the only ones that come to mind.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi