Site menu:

Home > TechFiles

Keep your Computer free from Viruses, Trojans,
Spyware and Malware

A HelpWithWindows TechFile

Peter Clark

By Peter Clark,
Microsoft Most Valuable Professional,
Windows - Internet Explorer

Surfing the Internet these days is a hazardous occupation, but a few simple precautions will keep your computer free from infection in an increasingly hostile environment.

Use the suggestions below to ensure maximum security for your computer at minimum cost! Although this article is written based on Windows XP and Vista the basic principles apply to other Windows operating system versions too.

Windows and other Microsoft Software

Keep your Windows and other Microsoft software installations, e.g. Office, fully up to date by applying Service Packs and all critical updates issued by Microsoft through Microsoft Update on the second Tuesday of each month (also known as 'Patch Tuesday'). Note: Windows Update does not scan for other Microsoft software. Set Automatic Updates to Automatic or Notify - do not turn off Automatic Updates! You can set Automatic Updates from the Windows Control Panel: in Windows XP click on the Performance and Maintenance category and then on System. Select the Automatic Updates tab (Figure). In Windows Vista click on the Security category, next click Windows Update and then on Change Settings (Figure) - to receive updates for other Microsoft software products (recommended) click the menu item Microsoft Update on the Windows Update Web site (Windows XP), or click Get updates for more products in Vista's Windows Update Control Panel, which will open the Microsoft Update web site where you have to make your selection.

If you have not installed a Service Pack (SP) to Windows XP, Service Pack 3 is cumulative, but requires Service Pack 2 to be installed first; this is also cumulative and does not require SP1 to be installed first. To obtain critical updates and patches through Windows/Microsoft Update SP2 must be installed. Service Pack 1 for Windows Vista should be installed on all Vista systems.


Security Always run an effective firewall and ensure that it loads automatically at boot time. Note: The firewall in Windows XP SP2 and SP3 is more effective than that in SP1, but neither filters outbound traffic (traffic going out from your computer to the Internet). In SP2 and SP3 the firewall is ON by default, but in SP1 it is OFF by default. In Vista the firewall operates both inbound and outbound, but by default, most outbound filtering in the Windows Vista firewall is turned off.

A third party firewall is generally considered to be more effective and more configurable and usually works on both inbound and outbound traffic.

Some recommended free firewalls are:

- there are other firewalls of course: use your personal favourite.

You can check the effectiveness of your firewall at ShieldsUP - your system should be completely 'stealthed'.


Install antivirus software, keep it updated and always check that it is running when the computer boots up. Schedule a full system scan at least weekly and ensure that the virus definitions are automatically updated. It is recommended that email scanning is enabled in the antivirus software and disabled in your chosen firewall (if the facility to scan email exists there) to avoid possible conflicts. If you need to turn your antivirus off - often advised when installing software - physically disconnect from the Internet first.

Some recommendations for free antivirus software:

- there is other antivirus software of course: use your favourite.


Windows Defender You should always have antispyware software installed on your system and have it scan your system regularly.

What is Spyware? Spyware is a generic term used for software that behaves in a certain way, such as showing you advertising, collecting your personal information or changing the configuration of your computer, usually without first obtaining your permission to do so.

Warning: Do not buy or download any antispyware software without first checking the Rogue/Suspect Anti-Spyware Products & Web Sites from Spyware Warrior. At best you get a rogue program that is useless; at worst, they install spyware instead of removing it!

Here are some good freeware AntiSpyware programs. It is recommended that you have at least two or more installed; they will detect slightly different spyware programs and may miss others.

  • Windows Defender - this provides real time protection against spyware/malware, autoscans and autoupdates.
  • SpywareBlaster 4.1 - permanent blocking of over 10,000 known items of spyware, etc. Update manually once a week, but for convenience autoupdate is available for a few dollars.
  • Spybot Search and Destroy - an on demand scanner with an immunise facility to provide a degree of permanent blocking and works well in conjunction with SpywareBlaster. Update and scan manually once a week.
  • Ad-Aware 2008 - an on demand scanner. Update and scan once a week.

There are other reputable AntiSpyware programs, so use your favourite.

Internet Explorer

Internet Explorer Windows XP users who have not upgraded to Internet Explorer 7 should do so to take advantage of the enhanced security features - Windows Vista users already have Internet Explorer 7 by default.

Configure Internet Explorer for maximum security as outlined in this Article: How to surf more safely with Internet Explorer 7. There is also a version applicable to Internet Explorer 6: How to surf more safely with Internet Explorer (Windows XP SP2 version).

Set the cookie handling (Tools > Internet Options > Privacy) to Medium High (or High if you prefer).

Set Internet Explorer to empty the Temporary Internet Files folder when the browser is closed (Tools > Internet Options > Advanced and scroll down to the Security section). For added security place a check mark against Do not save encrypted pages to disk.

Turn on the popup blocker (Tools > Popup blocker) or use a third party popup stopper - the popup blocker in the Google Toolbar is very effective.

Turn on the Phishing filter (Internet Explorer 7 only).

Install IESpyads - a list of restricted sites which help to minimize 'drive by' infections while surfing.

A further layer of security can be added by installing a custom Hosts file such as the MVPS Hosts File. Alternatively the custom Hosts file in Spybot Search & Destroy may be used.


Set Firefox to automatically download and install updates

Outlook Express/Windows Mail

Outlook Express For maximum security Outlook Express should be configured so that messages do not automatically open in the Preview pane (View > Layout and uncheck Show Preview Pane). Suspicious emails, particularly those from an unknown source may then be deleted without opening them.

By default Outlook Express prevents the opening or saving of attachments which could potentially be a virus - in practice this means all attachments - not a very practical solution. The best advice is to enable the opening/saving of attachments (Tools > Options > Security), but to open only those that originate from a known source or are expected. Beware of forwarded emails with attachments.

More Outlook Express tips in this TechFile: How to Secure your E-mail against certain viruses.

General Security

Security The general security of your system may be checked by running the Microsoft Baseline Security Analyser which will highlight any areas in which the system security is compromised and offer solutions to any problems found.

The security status of commonly installed programs such as Adobe Reader, Adobe Flash, Quicktime, Java, etc can be readily checked using Secunia Software Inspector and it is recommended to sign up for the free email notification service of software security updates.

Remember that the performance of your antivirus and antispyware software will be compromised if the definitions are not kept up to date. Your firewall should also be updated - most have automatic notification of updates.

It is advisable to keep away from peer to peer (P2P) file sharing sites which are often a source of viruses, etc or at least be aware of the risks involved. Even if you are using a "safe" P2P program, it is only the program that is safe. You will be sharing files from uncertified sources and these are often infected. P2P file sharing is a major conduit used by the 'bad guys' to spread their wares.

Personal Footnote

My main computer is set up essentially as outlined above and is connected to the Internet 10/15 hours a day. Apart from the very occasional piece of harmless adware which is not detected by the current definitions of my real time antispyware scanner (Sunbelt CounterSpy), but which is often detected by Spybot or Ad-Aware I have never been infected by a virus or Trojan.

More information & help with your computer (security) problems can be found on our Support forum.

Give your comments on this article.