Just to put the record straight on a 'few' of the inccorect posts and quotes in this thread......
The current disc drive industry standard for specifying acoustics is sound power, measured using multiple microphones (usually between 8 and 12) arranged in a sphere around the product to measure the sum of all noise from the drive.
All major OEMs require acoustic specifications using sound power rather than sound pressure, as it is more representative of end-user noise perception. Specs for HDs noise is measured in 'bels' - A decibel (dB), equal to 0.1 bel.
Seagate is by a long shot - the largest HD manufacturer and has two major assembly plants. Wuxi in Jiangsu (China) and Ang Mo Kio (AMK) in Singapore. Both use the same Seagate built motors and spindle assemblies.
Seek Noise will usually be 5bels louder than Idle. The Fly-height, HGA head type (Perpendicular in this case) - speed of operation, motor type and no. of discs all have massive effects on drive noise (as does the sound dampening properties of the drive case) - so faster /larger capacity drives are usually much louder.
Seagate is currently making the transistion from metal bearing Motors to fluid dynamic bearing motors (or FDBs) in its desktop lines (although they have been used in medalist drives for a few years now) - This is the reason there are two different type of Spindle motors on the drive pics.
Whether you have a pink, blue or spotted brown drive resin make absolutely no difference to its acoustic rating - Some Pink drives have fluid Motors - Some blue drives have metal bearing spindle motors. AMK and Wu assembly sites use both (and many different coulours of resin)
More importantly - most drive manufacturers give operating noise specs on their drives. Seagate do for all their drives.......and the 7200.10's operate at between 2.5 or 2.7bels - and if they don't - you can quite easily return it for a full refund. See the website (they also have pages of info on bearings/motors/acoustics etc etc)
Some high performance drives (15,000 RPM server types - Cheetah SCSIs for example) operate at much louder specs (around 3.5 - 4bels) - these really are noisy gits.
Oh - and by the way - I work in the the largest Hard Drive and Tape Drive recording head factory in the world
and it belongs to Seagate in fact - so if you really want the info feel free to ask. And please don't quote about things you aren't sure about -it gets annoying reading it.