Security is an issue in two ways. On your computer you may inadvertently wipe your contacts list or it may be an issue of external protection for your whole office.
One PR company recently had a break in. The most devastating damge was not done by the thieves taking the computer. It was that they took the office contacts file with the machine and there was no backup.
Staff had to start ringing round to one contact, getting the correct details and then asking the contact the number for the next on the list. It was not only very embarassing for them but extremely costly and took several weeks to put right. All because there was no back-up file stored separately.
Again, when you start small, a pack of guard dogs patrolling nightly would be taking it to extremes but it is something to consider. Putting vital computer disks into lockable and fire-proof boxes is a relatively cheap option - it also means that you have a record if your computer fails.
Having your computer locked to the desk is also a relatively cheap way of stopping thieves taking the machine. But, be warned, hacked off thieves might take their revenge by smashing the machine anyway.
Smoke alarms are a sensible precaution for any home or office and cost a few pounds from the local DIY stores. Burglar alarms are more expensive but a side benefit of installation might be that your household insurance premium falls.
Even locking the drawers on your desk might be a smart move if it stops your toddler ransacking your computer disks or scribbling over your contacts book.