I have been trying for hours to get ImageMagick working on my localhost (running XAMPP 1.8.3 on Windows 7). I have checked and tried literally every solution that I can find
After spending many hours trying to get this blasted thing to work (Windows 7, 64-bit), with no success, I decided to look at other systems to see how they handled the problem. What mediawiki did was simply NOT USE the ImageMagick/PHP extension! They call the ImageMagick convert.exe program directly and use the result (see includes/media/Bitmap.php in the mediawiki package).
You can't really blame people for abandoning the PHP extension, since apparently it has to be compiled with the "right" ever-varying compiler and matched at least with apache and ImageMagick builds. What is surprising about the situation is that this problem has been going on for over five years and it still isn't handled.
So my "solution/answer" isn't really one, it basically is to call ImageMagick a different way to avoid the problem, like mediawiki did.