Method 2 of this KB article explains how to enable searching files of unknown type: http://support.microsoft.com/default.aspx?scid=KB;EN-US;309173
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:
- Click Start, and then click Search (or point to Search, and then click For Files or Folders).
- Click Change preferences, and then click With Indexing Service (for faster local searches).
- This particular step is optional; personally, I don't enable this setting.
- Click Change Indexing Service Settings (Advanced). Note that you do not have to turn on the Index service.
- On the toolbar, click Show/Hide Console Tree.
- In the left pane, right-click Indexing Service on Local Machine, and then click Properties.
- On the Generation tab, click to select the Index files with unknown extensions check box, and then click OK.
- Close the Indexing Service console.