My understanding has been that if your drive supports ATA 66/100, then you're supposed to use an IDE cable with a blue end, and a grey connector in the middle, and a black one at the end. You plug the blue one into the primary IDE controller (which is usually a blue socket on ATA/66/100 motherboards. Then you connect the black cable to the hard drive and preferably set it to cable select, then you use the grey connector for a slave drive, if you have one. I'm making sure the same is true in my case, except the connectors are red instead of blue.