This is just some short notes on how you can manage to install the free VMware 5.1 Hypervisor on a HP Z600 Workstation.
I assume you have already downloaded the installer from http://vmware.com

As always when you would like to utilize virtualization in your CPU you have to enable the following BIOS settings

• Advanced Chipset settings > Intel VT-D > Enabled (Allows passthrough of hardware to a VM)

 

• Update your BIOS to the latest version
• Disable “Max CPUID Value Limit” option in BIOS

Without making this change in BIOS the installer would stop with the Purple Screen Of Death (PSOD) and the error message “can’t detect the last level cache”.

If you have a old BIOS that does not support booting from a GPT partition then you need to change this at the beginning of the installation.

Press Shift+O during and type in space and

formatwithmbr

The boot option will now look like

runweasel formatwithmbr

You should now be able to install ESXi 5.1 on you HP Z600.
This might work on other HP models as well.