Following a malware attack last week which targeted a known flaw in IE, like so many other attacks, the US-CERT recommended using alternative browsers thanks to their increased security. Microsoft is hurriedly trying to increase IE's security with the Windows XP Service Pack 2, but it's not fast enough for many.
In a vulnerability note released by US-CERT, it says "there are a number of significant vulnerabilities in technologies relating to the IE domain" and that "it is possible to reduce exposure to these vulnerabilities by using a different web browser." Well, they're right.
The latest "extremely critical" IE bug has still not been patched by Microsoft. µ