Quote - Agree with what's been said above.

Stability issues in Poser seem to be almost always memory related; sometimes it just disappears or freezes, other times it's more polite. So go for as much RAM as your system will handle or that you can afford.

Regarding Operating System: I've been running a dual boot with XP Pro and Vista 64; up until now I'd have unhesitatingly recommended XP Pro. However, I've recently installed the (beta) SP1 for Vista 64, I've doubled my RAM to 8Gb, and I've cut down all the GUI crap to a minimum. 

Result: Poser 7 now runs a whole lot faster on Vista 64 than XP. In fact, Photoshop and all the other stuff I use is faster too.

 

What are your system specs  or at least what motherboard are you running that gets you 8Gb RAM?

"Few are agreeable in conversation, because each thinks more of what he intends to say than that of what others are saying, and listens no more when he himself has a chance to speak." - Francois de la Rochefoucauld

Intel Core i7 920, 24GB RAM, GeForce GTX 1050 4GB video, 6TB HDD space
Poser 12: Inches (Poser(PC) user since 1 and the floppies/manual to prove it!)