Consumer level drives (pretty much all SATA) are not as reliable as enterprise level drives (pretty much all SAS). Unsure of the differences mechanically, though they do tend to lag behind in capacity to consumer drives.
Generally, most drives are reliable, but can fail at any time, so backups critical.
The most unreliable ones we come across at work - bearing in mind we tend to stick to HP, Sun Microsystems, Netapps, EMC and Dell - are without doubt the Sun branded ones (they are rebadged). Bloody things always failing.
I have just got the Samsung Spinpoint F1 1Tb 32Mb cache one, delivered for £81, for my Media Center, and have to say I'm impressed with speed and quietness of it.
I should add that a 200G Maxtor in my PC (the one that started smoking) is banging about, non stop recalibrating, non stop retrying, but refuses to die, and still has not lost a byte of data. I refuse to replace it, want to see how long it will last

Those that have seen my Tech2 laptop will know that drive in that has been failing for years, but again won't die
