You need to activate the php_openssl extension. From the php.ini, you either have to uncomment or add the following line, and make sure the DLLs are in the appropriate directory:
extension=php_openssl.dll
You might have to copy some other DLLs into the Windoze's system32 directory as well. I don't remember all, but one that come off the top of my head is the libeay32.dll. Take a look at the install.txt that comes with PHP, it has a lot of info on installing extension and etc.
Cheers.