Computer hackers, password crackers and Trojan trackers are everywhere, and it’s more important than ever to protect yourself.

If you don’t, and your bank account’s defrauded, it can mean you’re liable to pay for it.

Luckily, know what you’re doing, and you can get professional anti-virus software without paying a penny.

This time of the year is one of the worst for viruses, as many of us are shopping online or checking bank accounts, the cyber criminals are trying to target our machines.

As such, the end of the year tends to have more of these invasions than at any other time.

Viruses aren’t easy to spot; they can be passed on in emails or even while visiting otherwise reputable websites.

It could simply be virtual vandalism with a hobbyist enjoying breaking your computer, or it can be criminal with people trying to monitor your bank passwords or even harness your computer to commit cyber crime on it.

If you’re not protected you could be liable.

If your bank account is defrauded, provided you have taken all necessary precautions, it’s your bank, not you, which must foot the bill.

When it comes to computer crime, it’s seen as standard practice that your computer has a firewall (more later), and up to date anti-virus software.

If not, you could be considered negligent, and may be forced to cough up for the fraud yourself.

Yet it’s easy to protect your computer, and it needn’t cost you a penny.

Step 1. Keep your computer updated

Most computers are run on Microsoft software, and that already has some built-in protection; crackers and fraudsters often try to break through this to exploit weaknesses.

As it learns about these, Microsoft issues updates, so make sure you’ve ticked `download automatic updates’, which you’ll find under ‘system’ in `control panel’.

Apple Mac users have slightly less to worry about, as there aren’t as many viruses lurking out there, but they too should make sure their machines are updated. If you are a high-tech Linux user, you’re probably more than capable of looking after yourself!

Step 2. Ensure your firewall is switched on.

Most computers include their own firewall software (or hardware), which prevents a host unbidden nasties hitting your computer.

The best way to describe it is a firewall is the computing equivalent of a border fence stopping things sneaking in the wrong way.

While anti-virus software is the border guard, question each bit of data that legitimately passes through to check there’s nothing hidden on it.

Even if you’re not techie, you should be able to find it in you computer’s control panel or options and check it’s turned on.

Step 3. Free antivirus software

Paid-for protection is likely to cost you roughly £50 a year, but there are ways of protecting yourself for nothing.

There are four mainstream free professional anti-virus software packages for PCs: Microsoft Security Essentials, launched earlier this year is completely free to users of `genuine Windows machines’ and is available for XP, Vista and Windows 7. As it is part of the windows package, many people will find it easier to use.

Avira Antivir.

The free anti-virus software of choice for techies. It’s fast and thorough, but you’ll need some technical knowledge to get the most from it.

AVG Free and Avast.

These have been around for a while and are very popular, though the new packages above are taking many of the current accolades.

For full step-by-step details on how to get them for free go to www.moneysavingexpert.com/antivirus

The reason many of these companies offer free programs is it’s a form of marketing; it helps build the reputation of the firms that produce them, which is useful for selling other programs, including corporate anti-virus software.

Also, they’d like you to pay to upgrade to more fully functioning versions of the software. Yet these programs should be enough for most home users, providing you download the regular ‘virus bank’ updates, so they can detect the latest problems.

Your bank may help too.

Alternatively, you may be able to get normally paid-for antivirus software for free for a year or so if you bank online. Barclays offer some customers Kapersky Internet Security, HSBC supply McAfee Virus Plus.

Step 3. Be aware of anti-spyware and adware

Anti virus software and a firewall should be enough for most home users. Yet there are other useful programmes out there which can help.

There’s free software that can protect you against spyware; in other words, it monitors programs you’ve chosen to download, to see if they’re surreptitiously checking what you’re doing on the computer and reporting it back.

You can also counter adware, which is software that sneaks onto your machine and opens up adverts to try and sell you things, depending on what you’re doing.

It’s also worth making sure you’ve got a back-up of important files online, on CDs/DVDs or perhaps on an external hard drive and see that your email is protected from unwanted messages, or spam, using a spam filtering program.

A full list of all these programs is at www.moneysavingexpert.com/antivirus

There’s free Office Software too.

Free software isn’t limited to programs that will protect your computer; for almost everything you want to do online there will be a high quality free alternative.

Perhaps the biggest of the lot is the free equivalents to popular Microsoft Office programme. It’s called Open Office and includes full word processing, spreadsheets, presentation software and more, and you can download it at no cost.

Although it doesn’t have all the best and whistles of the Microsoft programs, it’s probably more than enough for most home users, and they are compatible with most other programs of the same type, so you can share documents with other people.

This software is developed under the ‘open source’ model, which means it’s the result of collaboration between techies around the world who are keen to reduce giant corporations’ dominance.

And similar is available for everything from analyzing data to 3D graphics modelling. I’ve compiled a full list at www.moneysavingexpert.com/freesoftware