For those who don't have a Windows key (like my umpc) use the mouse to left-click-drag the title bar of one window all the way to left and left-click-drag the other window's title bar all the way to the right. Applies to all windows not just IE's.
My Computer
At a glance
Windows 8 Pro w/MC 32-bitIntel Atom 1.86 GHz2 GBIntel GMA 500
Computer type
PC/Desktop
Computer Manufacturer/Model Number
OQO 2+
OS
Windows 8 Pro w/MC 32-bit
CPU
Intel Atom 1.86 GHz
Motherboard
OQO 2+
Memory
2 GB
Graphics Card(s)
Intel GMA 500
Sound Card
IDT
Monitor(s) Displays
LCD
Screen Resolution
800 x 480 (portable) 1280 x 1024 (docked)
Hard Drives
64 GB SSD
PSU
9 Ah Battery (portable) or OQO Brick (docked)
Case
Shirt Pocket Sized
Cooling
Tiny Fan
Keyboard
Slide out (portable) DiNovo Edge (docked)
Mouse
Eraser head (portable) Logitech Bluetooth (docked)