Why are you using IE in the first place?
Chiding aside....
That little green button on the top left conner of the window will make the window resize to fit the page your viewing.
If you want to get full screen....
Drag the window to the left side of the screen.
Now click and drag on the bottom right hand conner of the IE window. Keep dragging until the window fills the screen.
Edit: Ah crap.
Thats how you do it in Safari.
Umm.... Well, IE should work the same way.