I downloaded php_xdebug-2.0.5-5.3-vc9.dll, added at the end of PHP.ini the following line:
zend_extension_ts=\"C:/Program Files/php5/ext/php_xdebug-2.0.5-5
use zend_extension instead of zend_extension_ts
and look carefuly "Compiler" , "Thread Safety" , "Architecture" and PHP Version parameters in phpinfo()
example my php info say
PHP Version 5.3.1
Compiler MSVC6 (Visual C++ 6.0)
Architecture x86
Thread Safety enabled
so i used Xdebug 2.1.0 / 5.3 VC6 (32 bit)