grep a string in different maps.

[william.a.george@gmail.com]

Hi.
I have a problem.
I'm using emacs on windows xp. I donwloaded some .exe file to be able
to run UNIX commands on window (it's called UnixUtils).
What I need to perform is to search for a string in files. Grep finds
the string if the files are in the same directory. But my problem is
that I want to perform this search on files that exist in other
directories.
A little description of my directory tree:
- SW (directory)
      - logical (directory)
      - terminal (directory)
      - OS (directory)
If I'm standing in the terminal directory then it is OK to find a
string among the files in "terminal", but if I want to find the string
when I'm standing in "SW" then it not possible. Grep cannot recurse
through the directories.
I tried this combination also: find . -name * -exec grep -n string NUL
{}
And I got a negative result too.

Can someone please help me to find a way to solve my problem?

Thanks in advance.