In Windows, just use the following synthax in the php command "copy":
copy("\\server_source\path", "\\server_dest\path");
You need permissions to copy files (check the configuration of the webserver you're using, the user who's running the webserver must be included with r/w permissions).
If you haven't permissions, run a
system("net use drive1: \\server_source\path password /USER:[email protected]");
system("net use drive2: \\server_dest\path password /USER:[email protected]");
then:
copy("drive1:\path", "drive2:\path");
You must know which drive letter from Z: down to E: are available on your server.