Error in creation of new Rails Project

Hi,

   I have followed all the instructions to install the ruby on rails
as said in the home page ( I think I have done ). But when I run the

rails new tickets

after creating new files and sub-directories the following message
appears

Using rack-ssl (1.3.2)
Installing json (1.7.3)
Gem::InstallError: The 'json' native gem requires installed build
tools.

Please update your PATH to include build tools or download the DevKit
from ‘http://rubyinstaller.org/downloads’ and follow the instructions
at ‘http://github.com/oneclick/rubyinstaller/wiki/Development-Kit
An error occured while installing json (1.7.3), and Bundler cannot
continue.
Make sure that `gem install json -v ‘1.7.3’` succeeds before bundling.

I have downloaded the DevKit also and installed it. But looks like I
am missing something in the PATH or Environment variables. Please
suggest.

If a solution is already provided please suggest.

Thanks
Anand