It's my personal experience, but I didn't see WD hard drive that succeeded
to work longer then 4 month without falling apart. I've always replaced
twice, and then had to replace to Maxtor (Quantum), which is by the way 5$
more expensive here for some reason. Making a hard drive that will live for
years, seems to be greatest WD problem. Anyway in RAID, you will be able to
replace the faulty drives forever without loosing any data, so this will be
less problem for you