"Windows Desktop Search 3.01 is an updated component of Windows that enables instant search on your computer.

Windows Desktop Search (WDS) 3.01 is a minor update to Windows Desktop Search 3.0 that adds: support for indexing UNC files, additional support for enterprise deployment, and stability improvements. WDS 3.01 installs on Windows XP and Window Server 2003, but is not needed for Windows Vista since the WDS component is already included in Vista. Windows Desktop Search 3.01 helps you to find, preview, and use your documents, e-mail, music, photos, and other items. The search engine in Windows Desktop Search 3.01 is a Windows service that is also used by applications such as Microsoft Office Outlook 2007 and OneNote 2007 to index application content and deliver instant results when searching within that application.
If you choose to install and use Windows Desktop Search, you can search for e-mail, documents and other files located on your computer. No information about the files on your computer will be sent to Microsoft as part of this process. Instead, Windows Desktop Search will index the content of your computer and store the index file on your computer. You can customize Windows Desktop Search to index only specified folders on your computer. Windows Desktop search will not store copies of e-mail or documents after they are deleted."