Hiya John,
I don't think that you can do the file frequency thing with windows, but you 'can' do the searching right in windows for terms inside files. You can tell windows search to search specific locations (such as a directory full of just your articles) and then tell it what words to search for and it will give you a list of all the files that have that search term in it's content. Just choose the selection for
All files & folders >> A word or phrase in the file name >>
enter the word or phrase and then set the location (choose the browse on the drop down) and you now have a list of all the articles with your key word/phrase in them.
Unfortunately that won't give you any totals but at least you can look for which ones
I'll assume there are quite a few different programs out there that can already do what you're asking though, I recall using a couple a bunch of years ago for game server files. Maybe try Google and see what you can find for Text search or something? Good luck on the rest of it