Comes with windows server 2008 std r2. Quad Core Intel Xeon Processor. 6gb of Ram up to 32gb, 4 hard drives.2x Dell SATA 250gb 7.2k rpm hd's, 2x Dell(HE103SJ) SATA 1TB 7.2K RPM hd's. Hot Swap, 4 drives total 3TB! 3gb/s. Raid Setup to protect data. 2x redundancy 400w power supplies. Power cable. Dvd drive. Genuine Windows 2008 r2 std.