According to a study (I do not know if it is real), it seems that people with low IQ uses Internet Explorer rather than other web browsers like, Firefox or Google Chrome.
"A significant number of individuals with a low score on the cognitive test were found to be using Microsoft Internet Explorer (IE) versions 6.0 to 9.0,"
You can read more here.
Actually I would say the same about people using Microsoft Windows instead of any other operating system.
To me the problem is that most of computers comes with Windows and Internet Explorer as default, and people with low IQ will not realize that they are not using the best software and they just do not switch to a better option.
If all computers would come with Opera or Firefox installed those guys would use that, and they will not switch to Internet Explorer, a funny note anyway.