This question is not asked enough by most people and is a very important topic. First and foremost, you need to keep your computer up-to-date with all the patches and updates for your computer. If you’re using Windows, that means you need to go to windowsupdate.microsoft.com on a regular basis to update your copy of Windows. You also need anti-spyware software to keep your system free of all sorts of junk that you can stumble across on the internet. Ad-Aware (easy to use) and SpyBot: Search and Destroy (advanced) are the two most popular tools for getting rid of spyware.

Another critical part is Antivirus software to keep out trojans and other backdoor programs are essential if you are the type that downloads a lot of software off the web. I used to recommend Norton Antivirus because it is very effective, but Norton has a very bad habit (in my opinion) of being a pain in the ass in more ways than I can count, so I only recommend McAfee at the moment.

A good firewall is also part of the equation. Windows XP has a built in firewall that does the job after you enable your firewall in XP. Kerio.com has a personal firewall that is free to download and use for non-commercial purposes, which I highly recommend. Black Ice Defender is an easier to use firewall, but costs $40. Do not get Norton Firewall. I’m really not trying to Norton bash here, because they make a lot of great products, but their firewall has had some serious issues integrating properly with Windows.