Windows Desktop Search 3.0 is now available for free download.  For full integration with Outlook, also install the Windows Live Toobar, which will take advantage of WDS 3.0 if you’ve got it.

Windows Desktop Top Search is the same indexing and search technology using in Windows Vista and Office 2007. It allows you to find any document or message on your computer literally as fast as you can type. 

Compared with Google Desktop Search, WDS is better integrated with the Explorer and Outlook and has higher quality previews. 

Windows Desktop search takes of the Windows Find File dialog (with the shortcut key Windows-F) and also fully integrates with Outlook, displaying it’s search result lists and previews direclty inside the Outlook WIndow, as seen in the screenshot below.