Windows 2000 Professional supports up to 2 CPUs for systems that require more processing power. Specifically, Windows 2000 supports Symmetric Multiprocessing (SMP), a setup whereby threads are distributed more or less evenly across system processors. If you installed Windows 2000 Professional on a multiprocessor system, you should have no problems because the proper Hardware Abstraction Layer (HAL) would have been installed during the installation process. However, if you are upgrading a single CPU Windows 2000 Professional system by adding a second CPU, you will need to update the HAL on the system. You do this via Device Manager. Expand the Computer branch, and choose Update Drivers from the Drivers tab in the properties of your device. From the Wizard, choose the ‘Display a list of drivers from…’ option and then ‘Show all Hardware from this device class’. You will be presented with options such as those below. The MPS-compliant driver is for non-ACPI systems. Note that you no longer use the NT 4.0 Uptomp.exe utility to upgrade to multiple processor support.