Quote from jjf:
I am wondering whether ... it [is] a security risk.
I'm a computer guy that just joined this forum and I wanted to throw in my 2 cents.
You have things a bit backwards, Internet Explorer is your security risk that was preinstalled in Windows. Using Firefox is your best way to mitigate that risk.
I'm an Information Security Analyst where I work and I have multiple certifications, one of them called Security+.
Use Firefox. Opera as mentioned is fine too. IE is your worst enemy and I recommend people use it only for trusted sites and/or ones that absolutely require it. In those cases, I'd email those webmasters and advise them that their site is programmed poorly for non-IE browsers.
Firefox is (for the most part) based on strict standards and IE is designed without any regard for standards.
Hope this helps