My advise - dont use rounded cables for HDDs. I have an Antec Cobra rounded cable and I dont like it at all. Waste of money. It is not even good to use on my Optical drives. A lot of problems with HDD data corruption whilst copying files, and bad CDR writing at 52x.
Which one do you use ? I have heard there are some good brands which have each of the 80 wires indivitually shielded - but then these are expensive. The Antec Cobra has some sort of single foil around the wires which is not very effective in preventive "crosstalk" (is this is the right word to use)
@medpal - I rememeber Sunny had a rounded IDE cable for sale here recently - he had posted a picture of the cable and it looked like a nice cable.