Lenovo THINKSTATION D20 TWR E5620 2.4G 4 GB 500 GB DVDRW W7P Networked Attached Storage 8910APU 11.6 in x 10.1 in x 1.3 in / 3.9 lbs Built-in devices: stereo speakers, wireless lan antenna, bluetooth antenna 4 gb (installed) / 8 gb (max) - ddr3 sdram Microsoft windows 7 professional Bundled with x200 ultrabase