Kinda a loaded question, but I'd like to get everybodies thoughts here on which would be the best OS system mated with which Poser issue, 7 or 8 or PoserPro

My understanding is that Poser Pro mated with a 64 byte Quad multi thread processor using XP PRO is still the best way to go? AND for new machines, the Apple surprisingly is apparently the easiest to put XP on.  Current Vista machines are a nightmare to change out with XP Pro.
SO?  any answers, questions, personal stories, recommendations and/or arguments?

I know/heard that the new $3K plus apple desk top pro is the meca of Poser render machines, but I can't afford one and I'm looking for a portable to go with my big Quad XP Pro, which I recently had a shop that sells apple rip the Vista from and put XP on it for me :)
I'm also bascially looking for a portable to do my set ups for and sample renders, ani's pre assembly.

Westcat