Precompiled binaries for each release are available from » PECL for a variety of combinations of versions, thread safety, and VC libraries. Extract the archive and put php_mongodb.dll in your PHP extension directory ("ext" by default).
Add the following line to your php.ini file:
extension=php_mongodb.dll
Note: Additional DLL dependencies for Windows Users
In order for this extension to work, there are DLL files that must be available to the Windows system PATH. For information on how to do this, see the FAQ entitled "How do I add my PHP directory to the PATH on Windows". Although copying DLL files from the PHP folder into the Windows system directory also works (because the system directory is by default in the system's PATH), this is not recommended. This extension requires the following files to be in the PATH: libsasl.dll