Windows 7 & Vista, includes Aero Snap feature that allows you to move and place windows in convenient locations and resize them easily. FreeSnap will help you in accomplishing the same via keyboard shortcuts easily.

FreeSnap

Manually resizing windows can be a pain, and getting them to line up along the side of the screen is an unwelcome dexterity test. With FreeSnap, you can move and resize windows with your keypad.

Just fire up the program, and you can use hotkeys to center windows or send them to all corners of the screen. You can use the “plus” and “minus” keys to resize windows without tiresome clicking and dragging.

Want that window to touch the right edge of the screen?  Press and hold the left “Windows Key” and press the right arrow.

Press Windows Key + ? to bring up the help screen.

Go visit the FreeSnap Home Page to get it.

You can add Windows Snap feature to Windows Vista using GridMove.