If you have Microsoft Internet Explorer 6 I strongly urge you to update to Microsoft Internet Explorer 7

There is a publicly available proof-of-concept code for a new vulnerability in Microsoft Internet Explorer 6

What that means is a remote, unauthenticated attacker could execute a script that would allow them to steal cookies, hijack a web session, or steal authentication credentials.

You can
get Microsoft Internet Explorer 7 here

I use Mozilla Firefox myself as I like the interface better and for better or worse it seems the bad guys are always targeting Microsoft products, so if I can use something with a lower profile I generally do

You can get Firefox 3 here