Fortunately, I had backed up my important files (especially my pictures), but I still found out I made two errors - the hard way. So let me share it:
[1] If you rip a lot of your CD’s to the computer for easy compilation or MP3 player use - make a back-up of those files. That may sound absurd as you still have the original CD’s, but as I am in the process of re-ripping the lot, let me assure you, just a few DVD’s burned with your MP3 files as back up saves an immense amount of time if disaster strikes.
[2] Make a list of your favourite web sites. Sure, most you can find again, but not those that you managed to find via via. I am now backing up all relevant links on a dedicated blog page.