Have you seen the prompt to "Download Windows Search to improve history and favorites results" in the new Internet Explorer 8? If you don't have Windows Search installed you'll soon see this prompt whenever you try to enter an address in IE8's Address Bar.
There are several options to take, details in the links below. Basically, you can choose to install Windows Search from the prompt in the Address Bar, or from Windows/Microsoft Update, or a direct download from here: http://www.microsoft.com/windows/products/winfamily/desktopsearch/getitnow.mspx
Or, you can choose to disable the prompt by clicking it once, then waiting up to seven days for it to disappear.
Or, you can "muck about" in the Windows Registry to make it go away now; details and automatic tool found here: http://www.winhelponline.com/blog/remove-windows-search-prompt-ie8-address-bar/ NOTE: I suggest you avoid this choice. It's just not annoying enough to risk messing up the Registry and rendering your computer inoperable.
I've successfully avoided installing Windows Search up until now. After reading this from Microsoft, I believe I've changed my mind and will now include Windows Search when downloading updates. http://support.microsoft.com/kb/968513 and http://blogs.msdn.com/ie/archive/2008/09/11/the-ie8-smart-address-bar-without-windows-search.aspx
However, I'll still avoid or remove Google Desktop!