I was mistaken in my previous post when I said my wifes 2.4 penryn MBP doesn't make this noise. IT DOES!
And so does mine still, I'm really dubious about the hdapm install thing and what it does, I have sent and email to mac Format magazine to see if they can shed some impartial light on this matter, i will also be making a call to Apple soon, to see if I can get some resolution on this.
BUMP, BLIP, PLINK, DING - Normal operating sounds, apparently.