mb_ereg on windows php 4.2.3 not available

Hi, php: 4.2.3 os: windows 2000 I've enabled the php_mbstrings.dll extension (via 'extension=php_mbstrings.dll' in php.ini) and have access to some of the mb_* functions, but I need access to the multibyte regex functions. These functions aren't available to me at this point (Fatal error: Call to undefined function: mb_ereg() in ...) These functions aren't even exported from the php_mbstrings.dll which I have. How do I get php to support the mb regex functions on windows? Can someone please point me to a pre-built 4.2.3 extension dll with the multi-byte regex functions in it? Any idea why they aren't enabled in the default distribution? Regards, Brodie.