>Anyone know of a readily-available tool that can search a bunch of files for a specific string?
>

You could always go low-tech. Open a DOS window:

for %a in (*.prg) do find /n "Use" %a

Substitute whatever string you're looking for in place of "Use", above. Redirect it to a file if the list is long:

for %a in (*.prg) do find /n "Use" %a >> output.txt

(Sometimes the old dog's tricks are just fine. <g>)