ESX offers support for several 64-bit guest operating systems.

See the Guest Operating System Installation Guide for a complete list.

64-bit guest operating systems have specific hardware requirements:

For AMD Opteron-based systems, the processors must be Opteron Rev E and later.

For Intel Xeon-based systems, the processors must include support for Intel Virtualization Technology (VT). Many servers that include CPUs with VT support might ship with VT disabled by default, so you must enable VT manually. If your CPUs support VT but you do not see this option in the BIOS, contact your vendor to request a BIOS version that lets you enable VT support.

To determine whether your server has 64-bit VMware support, you can download the CPU Identification Utility at the VMware downloads page: http://www.vmware.com/download/shared_utilities.html.