PHP com Win32 API

Fala galera... pesquisei e consegui achar uma formar de pegar o username do cara logado na rede, mas não esta funcionando.... olha o código e erro aí abaixoFatal error: Cannot instantiate non-existent class: win32 in c:\arquivos de programas\apache group\apache\htdocs\teste.php on line 3<?php$api = new win32; BOOL GetUserName( LPTSTR lpBuffer, LPDWORD nSize );$api->registerfunction("long GetUserName (string &a, int & B) From advapi32.dll"); DWORD GetTickCount(VOID) Returns the ms the OS is running$api->registerfunction("long GetTickCount () From Kernel32.dll");$len = 255;$name = str_repeat("\0", $len);if ($api->GetUserName($name, $len) == 0){ die("failed");}if (!($time = $api->GetTickCount())){ die("failed");}echo "Username: $name\nSystemtime: $time\n";?>