Thanks Tyger_purr - you're probably right about Space Navigator. I've used up my current 3D budget on the P8 upgrade, but I'll put this at the top of the list.

(Note to self: Stop wasting money on extra content when you haven't installed everything you've bought...)

Edit to add - only pity with the Navigator is that the list of supported apps drops significantly when you switch the list to Mac OSX.  Still Poser at least will work.