How to assign a program to a processor in XP or Vista

In Windows XP Pro or Vista, if you have a computer running multiple processors or one with a dual core processor, you can assign specific programs to use a specific processor or core. First you need to open the program or run the process. Then do the following:

1. Right click an empty space on the taskbar or press CTRL+ATL+DEL and select to start Task Manager.
2. Click the Processes tab.
3. In the left column, find the process you want to assign (for example, Winword.exe for the Word program) and right click it.
4. Click Set Affinity in the context menu. By default, both CPUs will be checked. Check only the CPU you want the process to run on (CPU0 or CPU1).
5. Click OK.

This can be useful if you need to keep one processor free for use by a particular program, or if you're running older applications that don't work as well with two processors.