Google Desktop Search 1.0
If you use Google, Google Desktop will be your new best friend. It indexes local files and e-mails, logs and indexes your AIM chats and surfed web pages, and can even recover content from deleted documents.
It is a positive review, but brings up a couple of negatives. It does not have the ability to do field-based searching (search the To field in your email messages) or to search within ZIP filed. In reading the posts to the article, it looks like you may want to do the initial indexing while you are not using the computer. Apparently, you can do both, but the indexing can use up to 100% of your CPU usage, so it slows you down.
That said, it looks like it is a very functional desktop search engine.