I'm a little confused on your description, You'd like to to move over to serial connection rather than IDE?
Of the two drives which is SATA? I assume the 160 drive? Yes, those adapters are sensitive and really would serve no purpose having them on a sata channel when they reside on a udma 66. Your raid question would come into play if you intend to get a second (160) drive. If house keeping is your only worry try some rounded cables. Otherwise unless you upgrade you opti devices and storage to sata and get a controller, there is not real gain in what you'd like to do ( or what I think you'd like to do).