I once made this mistake. ping uses ICMP, which doesn't have ports. You can telnet to port 80. You can also run
tcpview to see which ports are bound by which executables. For anyone who hasn't seen them before, Russinovich and Cogswell's
Sysinternals utilities are invaluable.
If you're getting a directory index when index.php is present, it's probably because the server isn't configured to look for index.php when a URL refers to a directory. Look for
DirectoryIndex in the server configuration and add 'index.php' at the start of the list of file names.