Attached Link: http://www.poserinstructionalvideos.com

I run P5 on three different machines --- 2 Windows 2K and one XP and all three run great.

I am one that thinks P5 Rocks. I am a little partial as my company has been working on instructional videos for P5. I can tell you that P5 is still a little slow and lacks open GL but other than that you can not even come close to the same value in any other 3D package. The material room is based on Renderman, the same type of material node set up that Pixar uses. Endless possibilities.
The cloth and hair dynamics would cost you thousands of dollars in another package.
The new properties and parameters pallet is worth the upgrade itself, giving you so much more control over your dials.

P5 has so much to offer that unfortunately gets buried by all the bad press from Curious Labs mistakes of release a buggy program. I would say that 95 percent (or more) of those bugs are fixed and if you are wondering if it is worth the upgrade, I say hell yeah.

Christian