If you are on a Windows Platform, create an import.reg file with the following code in it (where .phps is replaced with the extension of file you would like to search inside, such as .cfm .php or .xml). Multiple ones can be added by making copies of the registry key and replacing the extension.

{code class="brush: powershell"}Windows Registry Editor Version 5.00 [HKEY_CLASSES_ROOT\.phps\PersistentHandler] @="{5e941d80-bf96-11cd-b579-08002b30bfeb}"{/code}

1. Save file
2. Import in to Registry
3. Reboot

Now windows searches inside those files for you.

Not checked on Vista.