Putting both HDD's on one cable, and the roms on the other cable is a good idea. Before you need to do anything, you need to set the jumpers on the back of the new hard drive to the slave setting. On the hard drive itself, it should have a little diagram telling you where to put the jumper to make it a slave. On your IDE cable, there should be to places you can place a hard drive. The one at the very end is for a master drive, and the one in the middle, is for a slave drive. Throw your new hard drive in the slave position, and turn your PC on. Enter bios and make sure that it has detected your new hard drive correctly, and reboot your computer. Windows should now see your new drive. If you would like a more concise explanation, just let me know. I dont know how much you know about hardware, so its hard to tell the degree of detail to enter into, when describing how to do it