The emphasize of this study is to evaluate security issues for home users having a personal computer connected to the Internet. It focus on the usage of advantages and disadvantages when using a firewall while connected to the Internet. The hypothesis is that it gives a better protection to install and use a firewall compared not to do so, due to security flaws in the operating system. The prediction was tested on a home user's personal computer. The testwork was divided into two major tests, each of them performed with, respectively without, a firewall. These major tests were divided into five smaller semi­ tests. The first semi­test without a firewall suffered from a virus or worm attack resulting in loss of data and log files. During the other tests no successful intrusion was detected. The conclusion of the study is that usage of a standard configured firewall provides a better protection for home users than not to use a firewall; and it's beneficial to update the operating system and other programs with security updates as soon as possible when they appear.