How to Disable the Windows Vista Sidebar at Startup
I must admit that I'm not a massive fan of the 'revolutionary' new sidebar that was introduced into Windows Vista. I can't say I've ever truly found a single decent use for it other than to help make my Windows desktop look a little more attractive. If you're looking to disable the Windows Vista Sidebar - well, disable it from booting up when Windows Vista starts up - then this quick tutorial will do the trick.
First you need to be looking at your Windows desktop environment and have your Windows Sidebar activated for this to work; provided you meet this criteria, we can proceed. Right mouse click anywhere within your sidebar to bring up a menu and go to Properties.

You should now be looking at the main Windows Vista Sidebar Properties menu. You're more than welcome to tweak and tune your Windows Sidebar any way you see fit but for the purpose of this tutorial I will only be covering how to disable it.

I don't doubt you've already worked out how to do this but just for clarification: all you need to do is uncheck the option at the top of the menu that says Start Sidebar when Windows starts; by doing so you will be preventing the Windows Vista Sidebar from starting up with Windows ever again - unless of course you re-enable it.
You can however still manually activate your Windows Sidebar by going to Start > All Programs > Accessories > Windows Sidebar.
My Windows Sidebar has been replaced on my Vaio VGN NR11S by a Google Sidebar. If I try to bring up the Windows version, I am told that the Administrator only can do this. That's me!!
How do I do it - does anyone know?
Alan.
Same as above - Uninstalled Google (it came pre-installed on the laptop) - all of it.
Removed it's registry entries - all of them.
I've even tried to take ownewrship of the windows sidebar folder and files (these were not executable even by the system admin - thanks Google!!)
Looked for policy files - none that I can see.
I STILL get the message that the sidebar can only be changed by an admin. BTW - I am logging in as the administrator.
Same here, I have a sony vaio fz21m and basically have the same problem. I try opening "windows sidebar" and it give me somt crap about having to be logged on as administrator which i clearly already am. Why is there a "google sidebar" as well as a "windows sidebar". Such an annoyance and still found no solution to this day. Hope someone can help.
Hmm, after disabing and rebooting (no sidebar starts)
However, when you look in task manager, it is still there using up precious resources - even though it's not on the desktop or the task bar.
If you really need to keep Sidebar from running (on my system it would reset the "Start with windows" every time I changed power plans) follow the instructions below:
1. Take ownership of the \program files\Windows Sidebar folder (using the tool at http://www.google.com/url?sa=t&source=web&ct=res&cd=1&url=http%3A%2F%2Fwww.howtogeek.com%2Fhowto%2Fwindows-vista%2Fadd-take-ownership-to-explorer-right-click-menu-in-vista%2F&ei=_bgmSqTYHsfAtwepvLnfBg&usg=AFQjCNHvIIF8Q7NTY_fWn9TeUuC0KpxupA&sig2=AjuYqjlY_ByrWQt1HVy19A ).
2. Change your explorer view settings to show known file extensions (in windows explorer, hit "alt", click "tools" menu, click "folder options", click the "view" tab, and uncheck "hide extensions for known file types").
3. Change the file extension on Sidebar.exe to .vir or .bk
4. Bask in the glory that is your computer sans Sidebar!