No. I think you’re way, way safer using Firefox over IE, but now, according to security expert George Ou, Firefox now has more vulnerabilities per month than IE (you need to read the whole article to understand the data).
Read George’s blog here.
Click here to read an unrelated CNET story about Symantec’s recent statements on Mozilla browser security (“Mozilla Web browsers are potentially more vulnerable to attack than Microsoft’s Internet Explorer, according to a Symantec report…There is one caveat: Symantec counts only those security flaws that have been confirmed by the vendor. According to security monitoring company Secunia, there are 19 security issues that Microsoft still has to deal with for Internet Explorer, while there are only three for Firefox”).