I recently had a mild panic attack when I saw this on my computer monitor. The things nightmares are made of. Fortunately, we were able to save the hard drive long enough to transfer all of the data before it failed completely.
The reason I didn't have a major meltdown during the process is because I take the time to back up my files on a regular basis. I take A LOT of photos. At the end of each month, I upload them to an online storage site, transfer that month's files to my external hard drive and then reformat the memory cards in my cameras. It is a system that works well for me and I write it in my calendar at the end of each month to be sure I remember. While I'm transferring to the hard drive, I also drag over any documents that have been updated during that month and occasionally transfer over my internet bookmark files.
If you don't regularly back up your computer, I would recommend that you look at scheduling something soon. I have had many friends who have lost photos and once they are gone, they are gone forever.