Alternatively the MS Windows Start button on your keyboard is your friend. As was pointed out on here recently START+left or right arrow half maximises a program window to that side of the monitor.
You mean the Windows key. Windows/up to maximize, Windows/down twice to minimize, and you can also drag any window with your mouse to the left or right edge of the screen so it snaps to do the same 50% width thing. You can also drag it to the top to maximize or stretch the top edge of the window to the top of the screen to make it 100% the height of your screen without changing the width.
Windows key/tab to switch windows in 3D view. Alt/tab to see all the windows open and switch between them.
If you learn the hotkey shortcuts to your programs, even just the basics, especially those in the Windows, Adobe Suite & Office, etc. you'll improve your productivity immensely.
Windows 7 users go here and click "Show All".
Keyboard shortcuts
Windows logo key
Open or close the Start menu.
Windows logo key +Pause
Display the System Properties dialog box.
Windows logo key +D
Display the desktop.
Windows logo key +M
Minimize all windows.
Windows logo key +Shift+M
Restore minimized windows to the desktop.
Windows logo key +E
Open Computer.
Windows logo key +F
Search for a file or folder.
Ctrl+Windows logo key +F
Search for computers (if you're on a network).
Windows logo key +L
Lock your computer or switch users.
Windows logo key +R
Open the Run dialog box.
Windows logo key +T
Cycle through programs on the taskbar.
Windows logo key +number
Start the program pinned to the taskbar in the position indicated by the number. If the program is already running, switch to that program.
Shift+Windows logo key +number
Start a new instance of the program pinned to the taskbar in the position indicated by the number.
Ctrl+Windows logo key +number
Switch to the last active window of the program pinned to the taskbar in the position indicated by the number.
Alt+Windows logo key +number
Open the Jump List for the program pinned to the taskbar in the position indicated by the number.
Windows logo key +Tab
Cycle through programs on the taskbar by using Aero Flip 3-D.
Ctrl+Windows logo key +Tab
Use the arrow keys to cycle through programs on the taskbar by using Aero Flip 3-D.
Ctrl+Windows logo key +B
Switch to the program that displayed a message in the notification area.
Windows logo key +Spacebar
Preview the desktop.
Windows logo key +Up Arrow
Maximize the window.
Windows logo key +Left Arrow
Maximize the window to the left side of the screen.
Windows logo key +Right Arrow
Maximize the window to the right side of the screen.
Windows logo key +Down Arrow
Minimize the window.
Windows logo key +Home
Minimize all but the active window.
Windows logo key +Shift+Up Arrow
Stretch the window to the top and bottom of the screen.
Windows logo key +Shift+Left Arrow or Right Arrow
Move a window from one monitor to another.
Windows logo key +P
Choose a presentation display mode.
Windows logo key +G
Cycle through gadgets.
Windows logo key +U
Open Ease of Access Center.
Windows logo key +X
Open Windows Mobility Center.