I've had a couple of people tell me that they're hard drives have failed recently and they lost pictures, lots of them.
Pictures can be retrieved from failed drives, but it's very expensive.
So what's the best way to back up your pictures from your digital camera? Burn directly to CD-ROM or DVD from the card.
All computers these days have USB-2 ports that are very fast. Buy a $15.00 USB-2 card reader and a copy of Toast Titanium and back up those pictures before you put them on your hard drive. If you have a newer Mac, you likely have a SuperDrive that burns both CD-ROMs and DVDs.
In fact, the best thing to do is burn 2 copies to disc and have a family member store a copy at their house too. If you have a flood or a fire, all your discs are ruined as well.
Erik