Do you feel safe dealing with money on your computer? You probably should; most banks will give you a refund if hackers steal money from your credit card or bank account. To be safe, you may want to check with your own bank whether this guarantee is offered.

It is this guarantee that makes online financial transactions possible. You can't be sure your computer is totally secure, but you can be sure that your money is safe (assuming your bank offers this guarantee). At the same time, losing money and then having to claim it back is a hassle, so here are some tips about keeping your money safe online.

Nearly all online thefts happen on the victim's own computer. Occasionally online vendors are hacked and financial details stolen, but this is rare. Interception of financial details as they pass over the Internet is extremely rare, to the extent that the risk can be discounted.

It follows from this that you need to keep your own computer secure. First of all, don't volunteer information to hackers. If you do, they won't need to break into your computer at all! You get an email, which claims to be from your bank, your credit card issuer, someone you are supposed to have bought something from, or some similar company. For one reason or another, it is claimed that you have to confirm some security details. By confirming them, you give the crooks everything they need to empty your account.

You need to know that everything about an email can be forged. (At least, almost everything. But the things that can't be forged are subtle enough that only an expert can spot the problem.) An email claiming to be from your bank might not really be from your bank. Because of this, banks don't send emails asking for your security details. If you get one, it's almost certainly fake. It will send you to a site that looks like your bank, but actually just collects card numbers for criminals.

Do you have problems with:

• unexplained pop-up advertisements,
• browser toolbars that you can't get rid of, or
• your browser's home page changing for no reason.

If so, your computer has probably become infected with spyware. These programs install on your computer without your knowledge, and serve up unwanted advertising. You need an anti-spyware tool to remove it, such as Ad-Aware. Ad-Aware is free for personal use. Try to avoid downloading "gimmick" programs like screensavers, as these often install spyware on your machine.

Viruses are closely related to spyware, except that they spread from machine to machine by themselves. These days, viruses are normally used to take over groups of machines, which are then used for sending spam and other disreputable activities. The machine's owner is then likely to receive complaints, rather than the real culprits. Some viruses also steal online banking security information and the like.

Many computers these days come with anti-virus software, but make sure that it is installed and turned on. It should be set to scan incoming email, and also do a whole system scan every week or so. It is important that this scan runs automatically. If you rely on starting scans manually, you are too likely to forget. The anti-virus software will also need to download new virus definitions occasionally (because new viruses are released all the time). This should also happen automatically.

If you don't have anti-virus software, you can get a list of suitable scanners here.

Next you need to stop hackers connecting to your computer directly, and breaking in. To do this, you need to:

• Install security fixes regularly. If you have Windows XP, you should install Service Pack 2. Then go to the Control Panel and double click the Security Centre. A window will open with the option to turn on automatic updates. Click the button to turn them on. If you don't have XP, you will need to install the fixes manually from Windows Update. Try to remember to do this regularly!
• Use a firewall. If you have Windows XP, you should install Service Pack 2 as above, then turn on firewall protection in the Security Centre. If you have other versions of windows, you can get a list of suitable firewalls here.

If you do all these things, your computer will be more secure than the huge majority of Internet-connected machines. Most machines, in fact, are not secure at all. If you make life difficult for hackers, they are likely to go somewhere else!