I wanted to install rmagick on Win7 but it can't install:
Is there any way to make it work?
C:\>gem list -r rmagick
*** REMOTE GEMS ***
rmagick (2.13.1)
rmagick4j (0.3.7, 0.3.4 java)
C:\>gem install rmagick
Building native extensions.  This could take a while...
ERROR:  Error installing rmagick:
        ERROR: Failed to build gem native extension.
c:/ruby/bin/ruby.exe extconf.rb
checking for Ruby version >= 1.8.5... yes
Invalid drive specification.
Unable to get ImageMagick version
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.
Provided configuration options:
        --with-opt-dir
        --without-opt-dir
        --with-opt-include
        --without-opt-include=${opt-dir}/include
        --with-opt-lib
        --without-opt-lib=${opt-dir}/lib
        --with-make-prog
        --without-make-prog
        --srcdir=.
        --curdir
        --ruby=c:/ruby/bin/ruby
Gem files will remain installed in c:/ruby/lib/ruby/gems/1.9.1/gems/rmagick-2.13.1 for inspection.
Results logged to c:/ruby/lib/ruby/gems/1.9.1/gems/rmagick-2.13.1/ext/RMagick/gem_make.out
C:\>ruby try.rb
c:/ruby/lib/ruby/gems/1.9.1/gems/rmagick-2.13.1/lib/RMagick.rb:11:in `require': no such file to load
 -- RMagick2.so (LoadError)
        from c:/ruby/lib/ruby/gems/1.9.1/gems/rmagick-2.13.1/lib/RMagick.rb:11:in `<top (required)>'
        from try.rb:3:in `require'
        from try.rb:3:in `<main>'