Poser 4 works just fine in Classic (although the UI is a bit "dirty"). Because of the bugs in the way Poser interacts with QuickTime, I've found it more productive working in Classic than in regular OS 9. This is because when Poser crashes it only brings down Classic -- not the OS. In fact I frequently start up two copies when working on long animations. Just make a second copy of the executable. Since Poser4 is a Classic app, it doesn't multitask well when rendering, however. When not rendering, it works just fine. If you keep both executables in the same directory, they will step on each other unless you lock all the files in the Runtime folder. If anyone is interested, I can post a quick shell script that will do this. Otherwise, just copy the whole Poser directory if you can spare the disk space. I've written many multi-threaded applications: it's a lot easier than you think. Saying that threading an app is too hard is just a cop-out. I've found that once you grok the way threading works, you never want to go back to state-machine programming. WinXP, etc. are not SMP. They still run in master/slave configuration and you don't get the smooth performance that you would with an SMP operating system like OS X. Because of the way Mach shields the applications from dual CPU issues, you don't have the stability problems on OS X like you do in Windows.