I messed around and here's what I found..
I entered <a href="http://www.google.com">TEST</a> into the article window and it would show it exactly as typed.
If I hit the toggle button at the bottom of the article editing window and entered the same text it would show <a href="http://www.google.com> in the article
If I enter
TEST into the article it shows it exactly as typed.
If I hit the toggle button at the bottom of the article window and enter the exact same text it would show TEST as a link.
I would add that I was testing using FF. I will check IE and let you know.