You can see at the Dell website where they have issued a software fix to help quiet the noise on the super fast Hitachi 7200rpm hard drives that are in use on the Dell 8600 as an option. These are much faster than a standard 4200 rpm hard drive or even faster than an upgrade 5400rpm hard drive but they are noisier.
So, yes, if you want the notebook to run quietly the standard 4200rpm hard drives will be the best in most cases.
The 5400rpm hard drive upgrade is a happy medium where you will get 50% better performance over the 4200 but still at a lower speed and noise in many cases over the 7200rpm.
As I said, however, adjusting the performance settings on the 7200 Hitachi can quite it down and this is also used as an upgrade in the HPZT3000 / Compaq X1000 notebook I have (see X1000forums.com) although people have ordered it and put it in themselves (not available as option on HP website -- only 5400 rpm is)
I am wondering whether the faster the hard drive spinning speed is the louder the hard drive noise is. Also, would the faster hard drive generate more heat, thereby setting off the fan more frequently?

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