Yep, transfers from one hard drive to another will have improved in speed. The fastest hard drive runs at the same speed as the slower hard drive when its on the same IDE cable, so seperating them is a good idea. You'll also be able to copy CDs on the fly when both of your CD-ROMS are on seperate cable. Just make sure your CD-RW is using the Master cable, and switched as Master. Not exactly sure. I've always done a clean install when I change something major inside my PC, such as installing a new hard drive. You should be able to change the drive letters via Computer Management > Drive Management however.