Error in boot.rb after manual install.

I installed Rails manually. Now it creates the app nicely but when i give any script/generate command, it halts with following error on command prompt
./script/…/config/boot.rb:29: undefined method `gem’ for main:Object (NoMethodError)

                  from c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:21:in `require'
                  from script/generate:2

I am on Windows Vista and installed each component of rails as a seperate gem in this order:

  1. Activesupport
  2. Actionpack

  3. Actionmailer
  4. Activerecord
  5. Actionwebservice
  6. Rake
  7. Rails

What could be wrong.

Thanks and regards,