ThinkCentre M81 Quad Core i5 i5-2400 3.1GHz 4GB RAM 320GB Hard Drive Windows 7 Professional 64Bit DVDRW Small Form Factor Business Black Intel HD Graphics 8 USB Ports Display Port VGA Serial Port Desktop Computer Lenovo M81 Quad Core i5 3.1GHz (i5-2400) CPU 4GB RAM, 320GB Hard Drive 8 USB Ports, DVDRW Windows 7 Professional 64Bit