There are other threads about how to install Imagick on Windows 7 but no help for me so far. :(
(Maybe problems have came up with more recent versions)
I have followed these steps to install:
The program can't start because php5.dll is missing from your computer. Try reinstalling the program to fix this problem.
PHP Startup: Unable to load dynamic library 'C:\xampp\php\ext\php_imagick.dll' - The specified module could not be found.
Instead of using the latest version I tried downloading ImageMagick-6.7.7-5-Q16-windows-dll from http://ftp.sunet.se/pub/multimedia/graphics/ImageMagick/binaries/. That one actually worked with the php_imagick.dll (Imagick for PHP 5.5.x) from http://www.peewit.fr/imagick/.
This is not the latest version but it worked. (even without restarting the computer)