A better file search tool

Is there a better file search tool than the one that comes with Win98?

I want one that will search by the file extension. For example, I want
to find a file containing the word "beatles" and want only the .MP3
files. In the built in "finder", when I go to "Advanced", it wants me
to specify what program is used for MP3 files. Which in my case, I have
numerous programs that play music. There must be some add-on utility
that allows for simply searching for a word and the added file
extension.

Thanks