Just going to throw this out there, because I too don't want to lose any of my data, so I have up and done something about it.
If you want to spend a little bit more money, you can have better data security. If you look in my sig, "The NAS Box" is MY data security. It has dual 500 Gig drives running in RAID1. That means that I have 500 Gig of space in the enclosure, and the drives are mirrored. When I look at the drive in Window Explorer, it looks like it is just one drive... the DNS-323 automatically mirrors the data onto the second drive, so that in the event of a drive failure, I have an EXACT DUPLICATE of the data on the second drive.
Sure, it costs more, My setup was about $525 for the enclosure & the drives, but it will be WELL WORTH it. You don't even have to use a 500 Gig drive, you could use any 2 drives, but the mirrored portion will only be as large as the smallest drive.
Good luck!!