just a comment: If possible, you may want to try using the GD extension in PHP. I think, in most PHP builds, the GD extension is compiled in. If this is true for your ISP, you can tell eZ to use PHP's GD functions instead of ImageMagick. This removes the need for system calls (for images manipulation, at least).
You can check for GD with a phpinfo()-File or in an existing eZ installation in Admin Interface -> Setup -> System information, then look for "Extensions" in the "PHP" block. Or ask your ISP ;)