Seagate 1TB Serial ATA HD 7200/32MB/sata-6G. Brand new right out of the box this afternoon. As a matter of fact I built this computer last weekend with the same model hard drive and was have trouble and reported a clicking sound to the forum and they alerted me that it was probably the hard drive. Brought it in to COMP USA this afternoon and they tested it and confirmed the hard drive was bad and they replaced it but would not install it for me unless I paid. Brought it home, did it myself, then installed XP in about 2 hours and then files were copied and then the screen said your computer will reboot (explained above).