Question: I'm currently using ArcGIS 10 on a Windows 7 64 bit Macbook Pro (2.53 Ghz and 8GB of RAM) using VMWare. However, when I am using ArcGIS I find it quite slow even with Windows 7 (64-bit) optimized for performance (no shiny graphics). My work involves making some python scripts and testing them, and whenever I run them, that is also slow, but even opening ArcMap and adding a small shapefile takes a long time (30s to 1 minute).

Is it possible to make my python program in OSX, import the ArcPy module and somehow run them from the Mac side? I realize that ArcGIS runs on Windows, but I was not sure whether any of the ArcPy part can be run separately. Or, could it be quicker to use the 'Unity' feature on Vmware to run these scripts?

I would also appreciate any tips on how much memory/processors to allocate for the virtual machine. At the moment it is 1 processor, and ~4gb of RAM and I would expect it to be quite a bit quicker.

Answer: 
I am running ArcGIS 10 on a VMWare virtual machine with Win XP Pro. Performance is as good as expected, and it runs as fast as my 9.3.1 on my laptop (also XP Pro). VMWare is installed on a well equipped server, which properly has something to say regarding performance on the virtual machines. I access the virtual machine via remote desktop. I know this answer isn't that helpful, but I am only trying to say that ArcGIS 10 can run fine in a virtual environment. If I were you, I would try it on a Win XP VM, if possible, as suggested before.
I think this is possible. I do not use the Arc tool suite, but I have other programs that I run in Linux and Windows virtual machines on my Mac.

I only run the Linux or Windows specific code in the VM. Even then, I have mounted my OS X box in the VM, and work in OS X folders. Anything which does not require the VM is run on OS X, in those same folders, but from the OS X machine.

This also allows me to keep everything non-critical on the OS X side of the machine, so it is backed up with everything else, and the VM is not backed up, as that would required 5-10GB for even a small file change in the VM.