For a good detailed overview have a look at this website:
http://www.cert.org/homeusers/HomeComputerSecurity/ Basic protection involves:
*Active Firewall program
*Active virus program
*Regular update of the operation system
*Other programs – AGV, Norton, McAfee, etc
Windows Firewall is adequate for average home users.
In Windows 7 go to the control menu – select Windows firewall and activate to for “on” private networks and public networks not connected.
There are many firewall programs available but care need to be taken to select one. Many of them offer a free version but if not a spam website require payment after a period of time.
Anti virus programs:
While using the Windows defender or Bigpond antivirus programs are better than using none, a carefull selected one is more appropriate.
I have used AVG, their free program, for many years but have been using their paid version for additional protection for the last few years.
One of the biggest sources of income by Net operators is through selling their anti virus programs and it needs care to select one.
There are also many composite programs available bundling a firewall, anti virus, anti spyware, email attachment protection and extended scanning services.
If your online activities are above average it's worth looking at a suitable paid program.
Despite their claims there is no program which covers all aspects, each computer user should consider which option suits them best.
Review your position about computer security:
Check your computer that your firewall is activated.
Locate your antivirus program:
In windows 7 – click on your start icon – click all programs locate the program click on the program and ensure the program is active, on auto update and covers all aspects needed.
For Windows 7 firewall go to the control menu – select Windows firewall and activate to “on” – private networks and public networks not connected.
In Windows Vista or other versions of Windows simular instructions apply, if you need to, enter “security” in the help program.
Why do I use AGV ?
*It has been an effective program for me which I have used for many years on about six computers and many operating programs.
*98 million use their programs from free programs to advanced paid programs.
*It is highly recommended by non biassed reviewers