Hardware and performance

Hi I am trying to install mbstring on the following system: Windows 2003 Apache 2.2.6 PHP 5.2.5 moodle 1.8.3 It says that this is missing. When i try to install the extension from the msi installer i can not find the extension 'mbstring' I go to the php.ini and there is details on mbstring as stated as the follows: [mbstring] ; language for internal character representation. ;mbstring.Xlanguage= Japanese ; internal/script encoding. ; Some encoding cannot work as internal encoding. ; (e.g. SJIS, BIG5, ISO-2022-*) ;mbstring.internal_encoding = EUC-JP ; http input encoding. ;mbstring.http_input = auto ; http output encoding. mb_output_handler must be ; registered as output buffer to function ;mbstring.http_output = SJIS ; enable automatic encoding translation according to ; mbstring.internal_encoding setting. Input chars are ; converted to internal encoding by setting this to On. ; Note: Do _not_ use automatic encoding translation for ; portable libs/applications. ;mbstring.encoding_translation = Off ; automatic encoding detection order. ; auto means ;mbstring.detect_order = auto ; substitute_character used when character cannot be converted ; one from another ;mbstring.substitute_character = none; ; overload(replace) single byte functions by mbstring functions. ; mail(), ereg(), etc are overloaded by mb_send_mail(), mb_ereg(), ; etc. Possible values are 0,1,2,4 or combination of them. ; For example, 7 for overload everything. ; 0: No overload ; 1: Overload mail() function ; 2: Overload str*() functions ; 4: Overload ereg*() functions ;mbstring.func_overload = 0 ; enable strict encoding detection. ;mbstring.strict_encoding = Off There is no 'extension=php_mbstring' Any ideas????