your master drive has to at the end of the ribbon, the second hard drive should one located on the middle, the other end is connected to your motherboard. make sure that your jumper for the master is set to master. secondary drive should be set to cable select, I think that is what the other poster meant to say. go into bios, check to see that both drives are now visible. if not do 1. Set your motherboard to auto detect. (if would be helpful if u posted the model no of your motherboard) 2. go to the website of your mobo manufacturer, update your motherboard. Some motherboards cannot dectect large storage drives. 3. reboot your computer. Are u using RAID or SATA drives? Your Windows XP CD is it slipstreamed with Service Pack2 or is it a plain windows xp cd? lets start there then we will find a solution