Windows 2000 64-Bit Edition

Windows 2000 64-Bit Edition is an ultra rare operating system developed by microsoft on November 30, 2001, designed for PCs that has a 64-bit processor like the Intel Itanium.

Pros

 * 64-bit compatible
 * run x64 programs

Cons

 * takes a long time for drivers to work properly on 64-bit
 * very few 64-bit applications
 * Windows 2000 64-bit bluescreened every 24 hours due to driver issues

System Requirements
the requirements are high for the time, it takes a heavy configuration or a workstation to operate.