How to reinstall MDAC 2.8?

Because of a wrong entry in the registry databse, I try to re-install MDAC 2.8 on my Win2003 server.
The .exe seems to be ok and the installation ok, however, nothing is effectively done on the server.

What is the right procedure to follow in order to reinstall MDAC and ODBC drivers?
Thanks for your help.

Sorry!
Found mdac.inf in wondows directory and select "install"
Then I need to locate the excpeted file from c:\windows\i386 (popup was confusing me because it asked the CDrom 2 of sp2 and nothing useful can be found on the CD).
Solved.