Some guys have hacked the Sidebar feature out of Windows Vista and made a small package available to integrate this feature into Windows XP.
As you may have heard, the Sidebar from Windows Vista was leaked onto the internet weeks ago. ZoRoNaX and I have been working hard since PDC '05 to bring you the same Sidebar working on Windows XP. Although we have some wrinkles to iron out, we decided to put out our patch and a preliminary build of our new emulation library. Just download our small package, extract its contents to the same directory containing Sidebar and the 'Default Parts' directory, and launch patch.exe.