"If I back up about once a week and occassionally watch movies of the drive will I have to really worry about it failing or is that not too much use and failure is unlikely?"
A good question.
There are those who are fanatically devoted to the "Time Machine concept" that you MUST have a backup running continuously 24/7 as you use the computer.
I'm not one of those.
A once-a-week backup using clone software like CarbonCopyCloner or SuperDuper! will constitute more than the overwhelming majority of personal computer users do to protect themselves against data loss.
If you shorten that to a routine of once-every-three-or-four-days, you'll be even more protected.
If you haven't yet bought a backup drive, I would suggest this:
1. Get one of these:
http://www.amazon.com/Syba-Connecla...?ie=UTF8&s=electronics&qid=1253062702&sr=1-22
2. Pick up a PAIR of "bare" hard drives. I think Seagates are some of the better ones being sold right now. Check newegg.com or dealmac for good prices.
3. Use the SATA dock and CarbonCopyCloner to clone your "main drive" to each backup drive.
4. Do your backups in rotation -- that is, drive one today, drive two four days from now, drive one eight days, etc.
5. For even more protection, keep one of the backup drives "off-site" -- in a location OTHER THAN where the computer is, to ensure against fire, theft, etc. (even a fireproof data safe in the basement might work)
The opening thread title asks:
Do I really have to be worried with HD failure?
Answer:
No -- not if you back up.
Once you _start_ to back up, you introduce a measure of insurance against hard drive data loss. The very fact that one DOES back up -- even if infrequently -- is much more important, and offers much more of a chance of recovery (in the event of HD failure), than not doing so at all!