Oh no you aren't!

For the translation to less-idiotic:
A hacker can make a web site that will do bad stuff to your computer if you are using Internet Explorer. Additionally, a hacker can hack a well-known web site and add the "bad stuff code" to that site too. Switching to a non-mainstream browser, like anything but IE, will make you immune to this spesific security hole. Additionally, you will have less security trouble later too, as most bad guys attack the market leader, aka Internet Explorer.

What they can do to you varies. If you are logged in as a computer administrator, a hostile script can do stuff like deleting important files, start programs which you can not see, and use your computer to serve illegal files and similiar stuff. If you are logged in as a normal user, the script is as limited as you are.

Or something.