If you're simply transferring data, a plain vanilla parallel data cable will be fine (though slow). If you've got a CD-RW, it might be faster to burn a disk with the files to be transferred on it. For whole drives, using Ghost or Drive Image (
http://www.powerquest.com/driveimage/) is easiest, especially if you temporarily connect the new drive to the old machine's second IDE connection and do a direct disk-to-disk transfer.