This note is based on IE 8 but IE 7 users will still be able to follow it.
Go to Tools on the menu bar.
Click on Internet Options.
Click on the fourth tab Content.
Under the heading AutoComplete click Settings.
Make sure the last two boxes are ticked (IE 7 looks slightly different but it is still the last two boxes).
Click OK and OK on the options window to close it.
Type in your username and password as you normally would
Click Log In.
Click yes to remember your password.
Once logged in, logout to test that the username and password have been saved.
This time double click the User Name field.
A box will drop down with your username in the list.
Click on your username.
Your username and password should be AutoCompleted in their respective boxes.
Click Log In and you are done.