I hear horror stories of lost files fairly often, and have had to deal with the tragedy more than once (although never with my own personal files).  Today I received my latest and hopefully last backup device.  If you have important files, like photos, tax documents, or anything else like that, you always should keep at least two copies of the files.  The files must be on two separate physical drives, preferably an external USB drive.  This way if your main drive dies or your external drive dies you have at least one remaining copy of your files.  Apple makes this incredibly easy with Time Machine and it is easily the best casual backup solution I have ever used.  All the Macs that I installed at church have an external drive attached to them for backup, just in case.  For less than $100 it is easily one of the best computer related expenses you could have.  I went one step further and got an external drive that just happens to be fireproof and waterproof.  It can withstand a fire of almost 1600 degrees for about 1/2 hour and can be underwater (fresh or salt) for up to 3 days.  This will protect our important files and photos even if the entire building burns down.  It’s something that I hope doesn’t happen, but gives us a little peace of mind, just in case.  The extra fireproofing and waterproofing isn’t that much more expensive (this drive was around $200) but it adds a significant amount of space and weight to the drive.  Definitely worth it for features I hope I never have to use.