I installed memcached by reading this article on Windows7 but unfortunately i keep getting error Fatal error: Class \'Memcache\' not found in D:\\xampp\\htdocs\\test\\
So i have looked now for a solution. Here you can download some compiled extensions.
http://downloads.php.net/pierre/
The problem is that at the moment there is no memcache extension for PHP 5.4. this is the problem why your extension could not be loaded. You need the extension for the correct PHP version and Tead Safe for Windows.
So the easiest way is to work with PHP 5.3 if you need the extension.
The newest version of memcache is the version 3.0.6 but its a beta version you can see it here.
http://pecl.php.net/package/memcache
You could try to take the beta version and compile it with your windows system. But its a lot of work.