I would like to introduce some good, yet free, programmes that can help to keep your computer clean from virus, worms, trojans, adware and spyware.

For starters, the AVG Antivirus is a small, simple, yet powerful antivirus programme that can keep out most of the virus. It is as powerful as the Symantec Norton Antivirus, but Norton Antivirus takes up too much computer resources.

You can find more info here: http://www.download.com/AVG-Anti-Virus-Fre...tml?tag=lst-0-2

Secondly, the ZoneAlarm Firewall is another great programme. Its parent company is Checkpoint, and Checkpoint firewalls is one of the best in the IT industry. It is simple, small and effective for home users.

You can find more info here:
http://www.download.com/ZoneAlarm/3000-104...tml?tag=lst-0-2

Thirdly, the AdAware spyware cleaner is a powerful spyware and adware cleaner. It can detect most of the adware and spyware in both programmes and the registry. Although the free version doesn't have the real-time protection, but it is still better than most other spyware scanner.

You can find more info here:
http://www.download.com/Ad-Aware-SE-Person...02.html?tag=pub

All the above are free, if you use it as a home user.

Thanks.