Yes it will be noticeably louder in full operation, as long as its working alright make mental a note of its noises and listen for any drastic changes, otherwise don't worry about it. Your 100Gig should be a higher Rpm than the 30Gig so its going to make more noise.
Actually both of them are 7,200rpm drives (I dont settle for less). I'm not as worried much now because its been just as noisy since I got it like a month and a half ago. My schools computers dont sound any better either heh.
You have exceeded the limit use of your current pointing device, reboot NOW!