Make Windows XP Look And Act Like Windows 7,
It is very small, it works fast and can be used on all Windows versions (9x/ME/2000/XP/2003/Vista/2008(R2)/Win7), even though Peeking requires Windows 2000 or later.
It is not a 100% copy of the Windows 7 features, but rather an improvement!… The Shake function shakes the window for you and the Peek function allows real access to the desktop instead of just showing it. And it’s also an improvement of the Show Desktop icon in your Quick Launch Bar or the Windows 7 Show Desktop Button: contrary to the original one, this one only minimizes windows and leaves Sidebars and Gadgets and such in peace.
On top of this, version 1.50 added an all new function, called PeekTop: this only Peeks through “Always-On-Top” windows that might block your view and it makes the active window semi-transparent, so that you can work with it and read what’s underneath at the same time.