If you are security conscious or have to spend some time on less reputable web sites a great option is to use either Linux or OS X. Because the high majority of security threats which we are exposed to are designed to compromise Windows, by moving to a non-Windows operating system those threats no longer matter.
This is not true all the time, especially for spam and phishing, but the possibility of a virus or spyware is greatly decreased. The problem is, of course, that people are reluctant to move to a new operating system, even a free one. A solution to this is virtualization, or basically running one of these non-Windows operating systems from within Windows. This will enable users to create a virtual workstation entirely on their existing computer, something which will not interfere with Windows and will not require a separate computer or even a dual boot.
XYZ Computing
XYZ Computing