Computer security is not a joke or an abstract concept. Just as you lockup your car and office, you have to take computer security equally seriously. In fact, a breached computer system can be more damaging than a break in or a stolen car.

The ABC Melbourne computer help program last week had a caller whose business computer system was hijacked over the Christmas break. The computer was used to host warez. The owner of the business returned to work and found a two-thousand dollar Internet bill.

There a number of basic steps all business computer users should follow to protect their data.

1. Apply security patches.

Most viruses and many trojan horses use known software problems. Make sure the latest updates are installed on the computer. The Windows Update and Apple download sites will help you keep your computer secure.

2. Check firewalls and anti-virus programs

Firewalls help stop the bad guys getting in. Anti-virus programs stop them sneaking in. Anti-virus must run on all computers and it has to be updated at least weekly and preferably daily.

3. Check network settings and shares.

Having the wrong data shared is a big risk for all businesses. You should be careful about sharing the wrong data. The biggest risk to a business are the staff and owners.

Accidentally deleted data is the most common data-loss problem. Sensible sharing policies are essential. Only share what is necessary and you'll minimise accidents and embarrassment.

4. Check your backup system is running properly.

Backing up is an important part of security. Even with the best security, things go wrong, files get deleted and sometimes the bad guys do get in. A backup provides the last resort in the event of a catastrophe.

5. Change passwords.

As with physical security, nothing will stop a truly determined crook from getting onto your system. But a properly protected systems makes it harder for the casual thief or vandal to cause damage to your computer data.