Work has decreed that I run 64-bit Vista Ultimate. But I can't get any work done on the VMs because of my issue. :(
Your supposed issue is a phantom one, as I’ve said several times all you need is the “workstation” version of VMware, not the “server” version since Vista is a workstation O/S. VMware Player is also compatible with Vista 64-bit. But if you’re hell bent on running an incompatible product in an unsupported mode, you can disable several Vista security features such as requiring signed drivers and internal integrity checks, and possibly get it working that way.
http://communities.vmware.com/thread/81042