The separate HDD will make things a lot easier to install. You don't need to set up partitions and a dual boot. When installing Xp onto your new HDD make sure that you have your raptors disconnected and your motherboards boot priority set to your new HDD. Once you got XP configured and running on that drive, shut down your pc and reconnect your raptors.. Start it up again and let the pc boot into XP. Once in make sure that you see all of your drives in My Computer and can access and use them (your pc should configure this for you as there will be conflicts between the two OS's as all the files will be visible to the pc but it should do this automatically as you log in) finally restart your pc and change your boot priority to the raptors and boot into Win 7 and make sure that you can see your new hdd and its contents(again it should configure this automatically) There is a possibility that every time you want to start with the other OS, you will need to go into your BIOS to change your boot priority to the other drive. But apparently Win 7 has an automatic boot manager that will prompt you at start up to choose your OS when it detects more than 1 OS on the system, even when they are on separate drives.