From Atom Imp Software:
Using a separate thread for minimum system impacts AtomImpFileSearch searches all the files in a folder and optionally all the files in the tree of sub-folders for the existence of a text search expression in the file names and/or the files textual content. Various search options are available including: - search using literal text, wildcards, or a regular expression. - search case sensitive or case insensitive. - restricting or expanding the default textual file types. - limited the search parameters. - easy inspection of the results in programs of your choosing. In addition an extensive help system including links to video tutorials is available.