Windows Vista has a Windows Sidebar which has various gadgets inside it. You can add new gadgets to this sidebar. If you do not like an added gadget then later you can remove it. If you want to remove a gadget then you can follow the steps given in this article.
- If your Windows Sidebar is not running you can run it from Start Menu → All Programs → Accessories → Windows Sidebar. You can also run the Windows Sidebar, by pressing Windows Key + R, typing sidebar.exe and pressing Enter.
- Hover your mouse cursor over any gadget in the sidebar which you want to remove. You would see options for the gadget appear on the top-right of the gadget.
- Click on the cross on the top of the options to remove the gadget
If you want to know how to add a gadget in the Windows Sidebar, then you can read this article : how to add a gadget to the Windows Sidebar in Windows Vista.