It should be noted that hard drives are not good for archival purposes. You can't stick one on a shelf for a decade and expect it to be readable (even if you do still have a machine capable of accessing it). They're just not made for that type of thing.
Long term archiving of digital information is difficult. Look at the storage media you had 20 years ago and tell me how you'd read the data today. MFM, RLL, SCSI, ESDI, etc. hard drives. First, assuming the drives still worked (not likely), you'd need a proper controller which hasn't been manufactured in 15 years or more, pluged into an expansion slot that hasn't been included on a new machine in 5-10 years, and software capable of interpreting it.
If this is strictly for archiving, tape or optical media would be a better choice. They're more suited to sitting on a shelf for years at a time. But you still need to keep the media current and have more than one copy. Heck, preferably more than one copy on multiple forms of media stored in different locations. Two sets of tapes and two sets of DVDs. Check them annually. If you see any errors reading your test set, do a full restore of all your data and make entirely new sets on new media (probably upgrading to whatever's current at the time).
And, even if everything can still be read 5 years from now, it's still time to upgrade the equipment and media. Transfer everything to Blue-Ray and holographic storage or whatever is the current mix of affordability and reliability. Wait much longer than that and it could become difficult to find a single system that can bridge your old media and new. I recently moved and found a QIC-80 tape I made a decade ago. It was only by chance that I also ran across a QIC-80 drive. But the old drive didn't work with Windows 2000 or XP. I borrowed a 98 machine off the junk pile at work to read the old tape (which took 3 days due to all the retries) and copy the contents to an external drive which I then hooked up to a current PC.
