It looks as if your system is running a SATA150 or SATA 1 controller. If you order and use a SATA 300 or SATA11, faster drive, then you must configure the jumper on the rear of the drive to slow it down to SATA150.
well well, I have not ordered it yet, can I not just buy sata150 or the other one? I only ask because I looked inside and saw the existing hd is 7200 rpm and a seagate 160gb. I could not see the speed!