There is one thing wrong with this test : that PC was not an average home PC as it hosted a web server, which I suppose was active (remember the buffer overflow).
Average home PC don't act as servers, so don't attract web traffic.
Furthermore, the plethora of fake security and anti-spyware is very probably due to the nature of the surfing which was going on by the people using the PC. This is a variable which can differ wildly from person to person. Go to unsafe and dubious sites, and the risk of getting spy or malware will be much higher.
