Call to Undefined Functions

First off, I'm developing on WinXP Pro, using IIS v5.1. PHP v4.3.4

now, i've gotten errors calling the functions
scandir() and file_put_contents()

the error has been
Fatal error: Call to undefined function: scandir() in C:\dir\dir\dir\script.php on line 56

what gives?

scandir() is PHP 5 CVS only

http://us3.php.net/manual/en/function.scandir.php