Insert value of params between " if the string have a space:

<?php
// First you need to create a service, you only need to do this once
/*
win32_create_service(array(
    'service' => 'myphpservice',
    'display' => 'My PHP Service',
    'params' => '"c:\\my folder\myphpservice.php"',
    'path' => 'c:\\PHP\\php.exe'));
*/
?>

<?php
// First you need to create a service, you only need to do this once
/*
win32_create_service(array(
    'service' => 'myphpservice',
    'display' => 'My PHP Service',
    'params' => 'c:\\myphpservice.php',
    'path' => 'c:\\PHP\\php.exe'));
*/

$myservicename = 'myphpservice';

// Connect to service dispatcher and notify that startup was successful
if (!win32_start_service_ctrl_dispatcher($myservicename)) die('Could not connect to service :'.$myservicename);
win32_set_service_status(WIN32_SERVICE_RUNNING);

// Main Server Loop
while (1) {
    switch (win32_get_last_control_message()) {
        case WIN32_SERVICE_CONTROL_CONTINUE: break; // Continue server routine
        case WIN32_SERVICE_CONTROL_INTERROGATE: win32_set_service_status(WIN32_NO_ERROR); break; // Respond with status
        case WIN32_SERVICE_CONTROL_STOP: win32_set_service_status(WIN32_SERVICE_STOPPED); exit; // Terminate script
        default: win32_set_service_status(WIN32_ERROR_CALL_NOT_IMPLEMENTED); // Add more cases to handle other service calls
    }
    
    // Main script goes here
    
    sleep(10); // Run every 10 seconds
}
win32_set_service_status(WIN32_SERVICE_STOPPED);
?>

Don't try to call "win32_start_service_ctrl_dispatcher" too late in your code. You'd trigger a #2186 error : "The service is not responding to the control function." (from commande line) or a #1053 error : "The service did not respond to the start or control request in a timely fashion." (from services GUI).

Try not to load a bunch of PEAR classes before to register php script as Service like I did.

Another good hint, to get a verbose version of the return code, you can call "NET HELPMSG ###" from command line where ### is your error code.