Lenovo™ recommends Windows Vista® Business. S10 Dual-Core Intel® Core™2 Duo E6550 - 2.33GHz, 2MB x2 L2, 1333MHz FSB Intel® Core™2 Duo E6750 - 2.66GHz, 2MB x2 L2, 1333MHz FSB Intel® Core™2 Duo E6850 - 3.00GHz, 2MB x2 L2, 1333MHz FSB Quad Core Intel® Core™2 Quad Q6600 - 2.40GH z, 4MB x2 L2, 1066MHz FSB Intel® Core™2 Quad Q6700 - 2.66GHz, 4MB x2 L2, 1066MHz FSB Extreme Intel® Core™2 Extreme QX6800 - 2.93GHz, 4MBx2 L2, 1066MHz FSB Intel® Core™2 Extreme QX6850 - 3.