> I selected one virtual CPU for the XP load...primarily because I want to > run a couple more VMs and the guidance was to allocate one real CPU per > VM. My understanding is that Win XP will perform a fundamentally different install depending on whether it detects 1 or many CPU. So if you ever plan to reuse your VM with many CPUs, you should install it with many right away (and follow the tip above: install as Windows Vista, not XP). I had this problem with a Win XP VM that I installed with pre v3.0 versions of VirtualBox: after VBox introduced SMP I could not use the multi-processor feature since XP had been installed with one processor. Anyhow, now that I'm using KVM, for my test desktop VMs I tend to allocate a total of CPUs across the VMs higher than the number of my physical CPUs, since they rarely need CPU power at the same time but I want them to be able to run very smoothly if needed. > run a couple more VMs and the guidance was to allocate one real CPU per Which guidance are you talking about?