By default the Windows XP search will only search for text in files that are registered.  This can be changed so that it will behave like previous versions of Windows and search for text in all files whether the extension is registered or not.

To configure Windows XP to search all files no matter what the file type, obtain the latest service pack for Windows XP and then turn on the Index file types with unknown extensions option.

If you use this method, Windows XP searches all file types for the text that you specify.  This can affect the performance of the search functionality. To do this:

1. Click Start, select Run and enter ciadv.msc.
2. Click OK and Indexing Service settings will be run.
3. On the menu select Action, Properties.  Note that you do not have to turn on the Index service.
4. On the Generation tab, click to select the Index files with unknown extensions check box, and then click OK
5. Close the Indexing Service console.

Using the "A Word or Phrase in the File" Search Criterion May Not Work