as another David has already described, you can stop the autocomplete in most edit boxes using the autocomplete settings dialog which is opened from the content page of the Internet Options dialog.
However, one exception to this is the search edit box on the Google page - I don't know how to stop it coming up with suggestions based on previous searches.
Yes, any edit box in any web page. I apologize for not being able to explain
it properly, but I really find it annoying that whenever I am about to enter
some text, and if I accidentally arrow down, it predicts the text, and I can
read, for example, all what I had searched earlier in Google.