BOINC

BOINC (Berkeley Open Infrastructure for Network Computing) is the open-source program that many people use for grid computing. The program will detect and utilize all of the cores in your CPU. So if you have a dual-core processor, BOINC will crunch two WU's at the same time. With a quad-core chip, it will crunch four WU's. This will result in 100% CPU utilization, so make sure you're running at the stable speed. It will also increase your CPU temperature, so have a good heatsink.