Custom index and search tool

I have regular inflow of television transcripts being saved locally and need a way to index and search through them for particular keywords. What I need is: The ability to save a list of keywords to monitor within the texts and within a specific date and the ability to filter the search through fields which are given in the filename of the transcripts (i.e date_time_channel_programme). The most important thing is that I can save the keywords so I dont need to keep entering them when i need to do a search. I need a list with numbers beside them giving me the count of all the times the particular keyword is mentioned. Perhaps something like an RSS reader or google alerts but used to read documents saved locally. This would run under windows, so preferably someone who is a .NET developer.