Indexing ASP files

I have several hundred *.asp files in my documents folder that I want to be
able to search, but Vista is indexing only the HTML content of these files.
This doesn't really do much good since I need to search the actual code
content within these files.

Does anyone know how to override the default filter associated with *.asp
files so that it indexes the entire file instead of just the HTML content? I
tried going to Indexing Options, Advanced Options, File Types, but the
filter is set to "HTML filter" and can't be changed from the interface for
some silly reason.