[iBook] weird sound from new 60GB hard drive?

[Laura Bruce]

Hi everyone and thanks for your help choosing my new iBook. I replaced
the 30 GB/512 model G4 iBook 12 " with a 60GB version of the same
thing.

I transferred all my files and settings from the old iBook to the new
one with a firewire cable, and I removed all the unnecessary languages
using the Monolingual utility someone here suggested (thanks). I also
reinstalled the system software on the old computer, and have a blank
slate (personalised for her) for my friend who is purchasing the old
one. So far, so good.

I played a few songs on iTunes, and when the songs finished, I heard
this hissing sound. At first, I thought it was that the speakers were
still sending output, so I closed iTunes.

The noise persisted. (My iMac did this, btw.)

Then I shut down the computer, and restarted. I covered the speakers,
and still the noise. It's not from the speakers. The noise is coming
from the QWERTY section of the underneath of the keyboard. It's not
loud, and it's not a bzz bzz noise. Just a low frequency thing, like a
fan (?).

I think it is the new bigger hard drive. Could this be the case? If
so, I am going to go mad. I have the hearing of a beagle and this is
already making me crazy after just an hour or so.

What to do? Is the computer faulty? Is this a feature of the bigger
hard drive? I will happily get rid of it and revert to 30 GB model if
this is the price I have to pay.

Help?

Thanks. 
Laura