Now if you're using Windows 7 you may find the new Aero Snap very handy, but imagine it was more powerful.  Introducing WinSplit Revolution...a utility that allows the use of drag and go or simple key commands (my favorite) to position windows quickly in a bunch of helpful places.  Now you can position 4 windows in their own space quickly.  This is a must.  This program can also run portably to allow you to always have it with you on your flash drive.  It works on Windows 2000/XP/Vista/7 (x86 or x64 versions).

WinSplit Revolution site