I'm running P7 in Ubuntu 8.10. with Wine. It ran just fine under 8.04 as well. I've been using P7 in Ubuntu for quite some time now - almost daily.
There are issues with ATI cards, I believe, but that's why I trust in nVidia. 
 I have P7 running in VirtualBox too in a stripped down XP I tailored (chucking out everything not essential, created an ISO image and used that as an installation media).  

P7 works with minor quirks in Ubuntu. It crashes very rarely and renders faster than in Windows (I used to have Windows XP on the exact same machine earlier).  

In fact I'm rendering a scene RIGHT NOW in another virtual desktop. I used to have difficulties with OpenGL losing it's marbles while switching virtual desktops and Poser would go black, but those issues seem gone now ... besides I'm Gnome with full Compiz effects and eye candy so it's not a big surprise issues might surface when switching between Wine and Ubuntu native software. I also use LXDE as a window manager when I want to work more quickly and more reliably. Not that often though since Poser seems to behave quite nicely.