"Back up your computer," like "floss your teeth," is one of those pieces of advice that you're really supposed to pay attention to but many people don't. On Friday, the hard drive in my barely 8-month old work MacBook croaked with no warning whatsoever. My last full back-up was 10 months ago (from a prior machine). While most (but not all) of my work documents can be reconstituted from email and shared servers, my personal stuff can't. And since I usually take this laptop when I travel (my personal machine is a desktop) it had become the default place for me to dump photos when I'm the road. So nearly a year's worth of images are gone. A few lower resolution versions reside on Flickr, but a pet project -- which involved taking at least one photo a day for all of 2008 --is lost for good. Words fail to describe how crappy this feels.
Backing up is a pain but, as I've learned, it's a necessity. Now I'll probably upgrade to Leopard and buy a huge external hard drive so that I can take advantage of Time Machine. So, in my ongoing efforts to serve humanity as a cautionary tale, I say this: Back up. Do it now.
Update: Thanks to Instapundit for the linky. Some good advice from the commenters.

I suggest that you take a look at the version management software like Subversion or the older CVS. (Subversion is definitely better wrt capabilities). Most of them are free of charge.
Contrary to what people say, this software is very useful even for people with regular documents, not just software developers.
I have a dedicated subversion server (yes, privacy) in a serverhouse for USD 50 / month. This is not expensive even in the Czech Republic, where I live. This server has a RAID disk field with mirroring, so it is pretty safe against crashes. Also, it operates in air-conditioned room with UPS, which reduces the probability of disk failure further.
With Subversion, you can manage versions of any files, including documents and images. It can integrate nicely into Windows explorer, and you can fairly easily view earlier versions of your documents.
Of course, it needs a skilled system administrator to set up the server and teach you the basic use, but I think it is worth the money.
Posted by: Marian Kechlibar | March 12, 2008 at 03:48 AM
yeah i had an 11 month old macbook. hard drive croaked. Luckily I had used Time Machine and had updated backup the night before the hard drive gave up. Found getting the hdd replaced relatively straight forward and painless.
Since then have been using Time Machine more regularly.
Posted by: Manny | March 11, 2008 at 08:11 PM
We had a G4 hard drive at the office go down a few years ago one week after the warranty expired, and then a G5 did the exact same thing just over a year later, which had us giving the folks at macconnections a little talking to.
Both machines have worked fine since then, other than some library file conflicts with Adobe In-Design. But we are about to upgrade everything to Leopard so we can buy the 1T Time Capsule and make sure everything is being automatically backed up.
Posted by: John | March 11, 2008 at 07:06 PM
I'm very sorry to hear about it. It's something which we close our eyes to and hope it never happens. Very disappointing.
Posted by: aus.doug | March 11, 2008 at 06:44 PM
I'm very sorry to hear about it. It's something which we close our eyes to and hope it never happens. Very disappointing.
Posted by: aus.doug | March 11, 2008 at 06:43 PM
Go get Leopard and an external USB hard Drive and let Time Machine do it's thing. Never have to worry about backing up. Also check out crashplan. It's kind of like Mozy.
sanssoucy Hard drive crash. Mac PC or Linux it a fact of life.
Posted by: WD | March 11, 2008 at 05:47 PM
A good time to reflect on the last time you told a PC user, "Macs just work."
Posted by: sanssoucy | March 11, 2008 at 03:17 PM
Groove baby.
I have two work computers and a home machine. I use MS Groove to keep everything in synch. It's awesome. It's seemlessly like working on one machine, only it's three.
Backups just come along for the ride as it were.
Posted by: Greg O'Byrne | March 11, 2008 at 02:03 PM
sorry to hear that...you should think about an offsite backup system like Mozy or iBackup. Your data backs up every night (or whenever you choose) and if a catastrophe hits, like fire or earthquake, etc., your data is still safe and your new computer can be uploaded with all the files from the latest backup.
best
s
Posted by: steve | March 11, 2008 at 01:56 PM