I could not find any information about installing Phalcon on Ampps for Windows, so here is how to do it.
The following describes installation for PHP 5.4. If you are using PHP 5.3, the instructions are the same. Just use 5.3 where I have written 5.4.
Download Phalcon 1.2.3 - Windows x86 for PHP 5.4.0 (VC9) Place it in C:/Ampps/php/ext
Open C:/Ampps/conf/php-5.4.ini in Notepad Add extension=php_phalcon.dll at end of file and save