Neither P6 not V5i are currently 64 bit aware. Poser is long overdue for a core update to make it multiprocessor aware, never mind 64 bit (theoretically, that should be happening in the next version....). Current rumor is that that V6i is supposed to be a 32/64 bit hybrid app that will run on both kinds of OS...and we should see that one before the summer is over. Current versions of both -may- actually run slightly slower due to the fact that any 32 bit app is running in WoW, which is an emulation layer. But the OS would be in native mode, so the speed advantages there might offset it.