This can be done in 2 ways - depending on how you are using it.
If you are lauching IE from a shortcut, then right click on shortcut icon,
select properties and define the Run dropdown as Maximised.
Otherwise, open IE and resize the IE window (not using the maximise button
at the top right) by streching the window edges to the extents of the
screen. Now close the window using the SHIFT key. The next time you open
IE, it should be maximised. Note that you may have to do this again in the
future if the window is reset by a web page. If you have to do it again,
always ensure that the last IE window you close is a maximised one if this
happens and you close it with the SHIFT key pressed.
Hope this helps.
Martin