I'm apparently in the minority, but I really liked the sidebar in Windows Vista.  On a widescreen monitor, there is horizontal space to waste and it was really convenient to have all of my gadgets showing over on the right-hand side.  In Windows 7, the sidebar was removed.  Gadgets are still there, but to me they became less useful because they were either hidden below all my windows or obscuring them.  There was no way to have them always show and have windows flow around them.  I've just discovered a new gadget called 7 Sidebar that acts just like the Vista sidebar, but for Windows 7.  You can find it here if you too liked the look of the sidebar.