Protect Your Data.  Before doing anything major to a hard disk drive be sure to backup your data and follow the Rules for Working With Hard Disk Drives and Safeguarding Data.

Setting-up the Drives.  A hard disk does not have be mounted in a computer case to copy stuff to and from it.  Be sure the power cord is pulled, and simply set it on top of the case up-side-down so the printed circuit board is not shorted and plug in the cables   A shop computer in a desktop case is shown in the picture to the right.  Lay a tower down on its right side and set the drive on top of the left side.  Be sure to put something such as a  foam rubber pad under the right side of the case to protect it from scratches from loose screws. etc. that have a way of accumulating on workbench tops.

If your motherboard has two IDE interfaces, image and data transfers will go much faster if the two drives are set as Masters, the default setting for almost all new hard disk drives (with no Slave present ), and connecting each to one of the interfaces for the transfer.  That is, temporarily disconnect the CD-ROM and connect the hard disk drive in its place on the secondary IDE interface.  However, do not leave the drive on the secondary with the CD-ROM if you are going to use the drive frequently.  A CD-ROM can slow-down a hard disk drive.

    One would normally make a new drive the Master, especially if it is a 7,200 RPM drive and the old drive is 5,400 RPM.   Not only is it faster, the new drive should be more reliable and