I have been trying the new Desktop Search utility from Google. My first reaction is that it is good. Really, really good.
The utility lets search for a topic from your email (Outlook or Outlook Express), AIM chat logs, Word Documents, PowerPoint presentations, Excel spreadsheets and even web history. Easy to use, easy to configure. A very useful utility.
You install the software and it creates an icon in the task tray. It takes a short while to index all the data on your hard drive. Thereafter, searches are really fast and the interface is going to be familiar to anyone who has used Google. See http://desktop.google.com/screenshots.html for screenshots. Results are sorted by type, so you can focus on just e-mails or documents or whatever by clicking on the header bar.
The downside is that it requires a connection to the internet to use. It is NOT secure, which could create problems for some users and businesses. But for a consumer tool or in non-secure businesses, it is great.
The email functionality is superb. It can save you hours of clicking through threads to find what you need.
Google is targeting the functionality that Microsoft is planning on adding to Longhorn. At this point, I would say "Advantage Google."
You can check it out yourself from http://desktop.google.com/