Windows 7

New features

Double click resize part of border to maximize window vertically.
Drag a window till the cursor is in the middle of an edge of the screen and the window will fill a portion of the screen
Sound > Playback > Set Default now takes effect immediately for all apps instead of requiring you to restart an application that was started when a different playback device was set as default. Saves time if you use optical audio out on a laptop and change playback device frequently.
Screen snipping tool, useful for looking at changes to a program's output side-by-side