It's a truism in IT that there are two sorts of hard disks: those that are about to fail, and those that already have. Sadly, hard disk failure is a fact of life - and that's not even the most common cause of data loss. Accidental deletion, loss or theft of laptops and damage caused by malicious software all pose a threat to your data. Backing your data up is how we address this problem.
Knowledge of backup solutions often comes after long and painful personal experience! Here are some things to consider with your own backup system:

• Is it automatic? Will your backup system keep working if you/your secretary/your IT person/your intern suddenly disappears? Does it rely on someone being infallible? If so, you're using people for what computers are best at: doing repetitive, boring things.
• Is it tested? How often do you test your backup system? One client of ours had a system that a friend set up. Our client dutifully followed the instructions, safe in the knowledge his data was being backed up....until his hard disk failed and the backups were needed. Sadly, the backups were useless - and the first time they were tested was the first time they were needed. The moral? Check your backup system on installation and schedule regular checks thereafter.
• Is it offsite? Often, on-site backup is good enough for a small company's needs. However, you should also consider off-site backup. This protects you against incidents such as extensive theft and disasters like fire or flooding.