For all the criticism of IE for being "unsafe"... I've never had an issue. The most integral part of computer safety is between the keyboard and the chair; if the user is unsafe, then the browser won't matter. I'm not denying that security may be a problem with IE, I'm just saying that I've never had a problem with my computer that I could trace to using it.
To each their own, however. I just think it's a false sense of security. People bring in computers all the time that have fake AVs despite the fact they have a decent anti-virus already installed / running. They make the mistake of assuming they're completely protected when in reality they aren't. Using Firefox may make you "safer"... but it's definately not infallible.