Owned 3 brand new Western Digitals without any problems. Completely silent operation. Had a used 120GB one that had a bit of noise, but nothing major, works great still. All WDs I have work nice and fast with not a sound. newer WDs I've had: 160GB SATA, 320GB SATA, 80GB IDE, 120GB IDE. I've had countless older WD HDDs, some crapped out from old age, some still work fine.
My brother had a new Seagate 200GB SATA. It was the loudest thing in his system, to top it off it chirped now and then as well... It was ok on speed at first, but got noticeably slower as it got older. On the other hand, I got a used 160GB Seagate IDE drive that is nice and fast and silent... Had so many old Seagates, probably more good old ones than WD, but some still crapped out from old age.
Never had a Samsung.
Will forever stay away from Maxtor...
To pick one brand, Western Digital all the way.