It runs quick like a bunny on my new computer. Even the staid Navigation tutorial seems like fun when you've been away for so long.
I held off on playing SH3 for a while due to a desire not to have Starforce on a new computer. Picked up the Encore disk last month and although it doesn't have Starforce I wasn't having any luck with it until now.
I'll spread the word if I run into anymore Nvidia and Vista users.