Hard drive going bad?

Custom build with 3 WD Caviar SE16 hard drives installed. Primary drive is a 500 Gb unit, while the others are 250 Gb each, they are not set up as RAID
When I initially boot up my system I hear a whirring sound followed by clicking (about 5 distinct ones), this combination of noises happens about 5X then disappears, the system boots up normally, however.
Periodically my system will start making this noise again while in operation, once again system operation is not affected.
Does this sound like a hard drive going bad?
I've ran the WD self tests on each drive, no defects were shown.
Also, I have attempted to access the Toshiba website that supposedly had a recording of a drive going bad, but I cannot find it there.

I am considering upgrading the drives to 7200 rpm units, but would like to recycle my existing drives to another smaller system, what do you recommend?



OK, now that I have narrowed down the din to a bad hard drive, can anyone suggest replacements for what I have now?
I may consider a RAID array, 7200 rpm is a must
Any preferences to brands?
WD has left me with a somewhat sour taste
Reviews on Seagates from NewEgg appear to be mostly positive
This is not a gaming system, little if any graphics work is done on it
Audio processing (vinyl to CD) is done fairly regularly
My case allows for five 3.5 drives
Any suggestions?

Existing drives are:
WD 5000 KS
WD 2500 KS X 2

Edited by newbie in hawaii, 20 February 2009 - 11:04 PM.

Hard drive noises

http://datacent.com/hard_drive_sounds.php

Noises from the hard drive is normal...to a point. If the noises have changed recently, that could be a sign of a larger problem. Hard drives usually have a lifespan of five to seven years before they begin to fail.

Noises from the hard drive is normal...to a point. If the noises have changed recently, that could be a sign of a larger problem. Hard drives usually have a lifespan of five to seven years before they begin to fail.

Thanks for the response, however this noise is anything but normal
These drives are approximately 3 years old
I will take the time, remove the cover and physically source the noise

Hard drive noises

http://datacent.com/hard_drive_sounds.php

Thanks Mark for the link, the noise which most closely resembles the sounds I am hearing indicates a bad preamplifier. These strange noises started about 3-4 months ago
I guess I can expect impending doom shortly and will back up data asap