I could read something that looked like QuickView, which would make mine a Maxtor. Hard drives basically make two noises: bearing whine and head seeking chatter. When recording, my 6412 makes a loud, what I consider to be, seeking noise. However, I can only hear it when the TV sound is low or off.
My ReplyTV, with an 80GB drive I put in some time ago, makes the bearing whine noise, and believe me, that's a whole lot worse than seek chatter.
Having said all this, Seagate is considered to be making the quietest drives at the moment, although that is only considering the idle spin noise. It used to be that you could set a trade-off between the seek noise/seek speed (acoustic management), but I don't think the Seagates allow that anymore, possibly because the seek noise on their drives has been reduced overall.