Dan, the 0x5D error is UNSUPPORTED_PROCESSOR (see http://msdn.microsoft.com/en-us/library/windows/hardware/ff559072%28v=vs.85%29.aspx), perhaps your host computer's CPU does not support 64-bit guest operating systems or the BIOS is not configured to allow it?
See VMware KB 1003945 at http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&docType=kc&externalId=1003945&sliceId=1&docTypeID=DT_KB_1_1&dialogID=684240564&stateId=1%200%20684254821
Mathias