php.ini probably needs to read:
extension=ext\php_sqlsrv_53_nts.dll
Or move the file to same directory as the php executable. This is what I did to my php5 install this week to get odbc_pdo working. :P
Additionally, that doesn't look like proper phpinfo() output. If you make a file with contents<? phpinfo(); ?> and visit that page, the HTML output should show several sections, including one with loaded modules. (Edited to add: like shown in the screenshot of the above accepted answer)