You can import a Windows XP Mode virtual machine and run it in Workstation Player. When you import a Windows XP Mode virtual machine, Workstation Player creates a new virtual machine in VMware runtime (.vmx) format. You can power on only one Windows XP Mode virtual machine at a time in Workstation Player.

OK I was going to drop this thread because I assumed VMWare was not compatible with Windows XP Pro x64. But after having reviewed the product documentation I can see that VMware does indeed support Windows XP Pro x64 as a host.