Note: See also the follow up to this article about some of the Linux Backup Solutions
Some things are learned the hard way and the importance of taking backup was among those. While I will not get into the details about how to take backup I just want to stress on the importance of backups. Just consider one of the following real-life scenarios:
1. There is a huge power fluctuation and your entire hard disk gets destroyed.
2. You are moving your PC / laptop around, it suddenly slips from your hand and resulting in your hard disk crashing.
3. You are very sleepy and accidentally delete some important folder.
4. You have all your blogs on wordpress or some free hosting provider. You write about some controversial issue and your blog hosting provider deletes your entire site without giving you any explanation (ever bothered to read the agreement to which you agree while opening an account?)
5. You access your mails from everywhere. Someone who is really pissed off with you by some means gets access to your account password and deletes all your mail.
These are all very real life situations which I have either encountered or seen someone else encounter. Hence I strongly suggest that you take regular backups of all your important data (it might not be necessary to take Operating System backup but if you do it will be helpful for recovering quickly in case of an eventuality).
I use dar combined with SaraB and cron to take nightly backups to an external hard disk. And then once in a month I copy these backup files to DVD for offline storage. Apart from dar, there are many tools available in linux for helping you to take full and differential backups. I personally prefer dar because it is simple and has some nice features such as compression and automatic splitting if the backup image size exceeds a particular size so that it will fit on backup media such as CDs / DVDs.
Similar to linux, Windows will also have many backup software available for free including the backup utility which ships default with Windows. Also if you google around, you should get articles related to how you can take backup of your blogs/websites and emails.
So don't be a fool like me and wait till disaster strikes. Instead start taking backups today and sleep peacefully.