AimAtFile finds document files by contents.

AimAtFile Fast File Search - description of program

AimAtFile is an effective way to find document files by their contents. It lets you search for files of many types: MS Office documents, HTML, PDF, plain text, media files and others on a desktop computer or in a network. The content search functionality is based on Microsoft Indexing Service included in Windows 2000/XP/2003. AimAtFile provides a document preview. You can see the contents of found documents without opening them in their editing programs.
Microsoft Indexing Service scans files in the background as a low-priority process and AimAtFile requests this index to return search results instantly. Unlike the most of third party file search utilities AimAtFile does not scan all files each time you try to find any file. Some of third party search tools use their own indexers. Windows already includes the native powerful Indexing Service so it is not necessary to install additional indexers into the system. The only thing you need is a right tool to query the built-in Indexing Service. AimAtFile Fast File Search is the tool.
AimAtFile Fast File Search allows to search network shared folders. So it gives an opportunity to search for documents in your corporate Local Area or Virtual Private Networks.
The program is easy to use. The interface is very intuitive. Run the program, type a query in the Query field, click Search and you will get a list of relevant documents. A query may be simple (just words that target files contain), a Boolean expression, or a more precise query written in the Indexing Service query language.