Windows: exec-path not working?

[Elena]

Hello,

I was trying to use the "M-x grep" under Windows, but it was failing
since "grep.exe" was missing. I downloaded GnuWin32's grep (it worked
under command line) and appended its directory to exec-path:

(setq exec-path (append exec-path (list "C:/gnuwin32/bin")))

and checked it. Anyway, running "M-x grep" still couldn't find "grep".

Then, I set Emacs' environment PATH by means of "setenv" and "grep"
got found.

Shouldn't be exec-path and PATH achieve the same goal under Emacs?

Thanks.