Hi,
I had my share of problems with hard drives,
I've started with a 1.6 gb seagate, which died completely for no apparent reason after a few weeks. It got replaced with a 2.1 gb seagate, which worked for at least 3-4 years, but it started developing bad sectors, so I've replaced it with a 40 Gb WD (this was around 8 years ago), the WD is still working, but I wouldn't trust to actually use it for any kind of data.
Shortly after that I got me a 60 gb maxtor, which again started to fail after 1.5 years, it was a problem with the PCB, I believe the power cable wasn't making contact all the time, because some wire got interrupted. It got very noisy and hot, but I've kept using it, making backups on DVD's almost on a daily basis.
Two years ago I bought a 200 gb seagate, which is still functional, but it developed bad sectors, and once you have a few of those, other will come and it's usually a bad idea to keep on using them.
Around a year ago I bought a NAS with a samsung 1 TB drive in it, which is still working, although you can imagine that I use it mostly for backup purposes, so the drive doesn't see to much action.
Almost at the same time I also bought 2 seagate 1 TB drives (9 months ago), unfortunately from the faulty Barracuda 7200.11 series, which have the firmware SD15, which has some problem that makes the drive fail after around 8 month of usage. I already lost one of them, the second one is faultless, at least according to the SMART error log. I'm planning on buying 3 more 1 TB drives, probably from Seagate, Barracudas .12 and I will be on the look-out for possible problems via the forums.
I also assembled a few dozen computers for friends and colleagues, but most of them are still happy with their hard drives. Only some maxtors have failed until know.
I believe that getting a good hard drive depends on luck, but not entirely. There are surely manufacturers who are better in what they do, and having 3,5 years of warranty is also a good sign that they trust their drives.
It also depends on what you do with your hard drives, because you can't expect the same lifetime from a drive 24/7 used in a file server compared to the drive from my mothers computer, which she uses only to play Zuma one time a week.