Testing Problems

I am following this tutorial http://www.aidanf.net/rails_user_authentication_tutorial to create a basic user auth system, but when I try and run the test I get a slew of errors with rails:

d:/ruby/lib/ruby/site_ruby/1.8/rubygems.rb:196:in `activate': can't activate rai ls (= 1.2.2), already activated rails-1.2.1] (Gem::Exception)         from d:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb: 32:in `re quire'         from d:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/ active_suppo rt/dependencies.rb:496:in `require'         from d:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/ active_suppo rt/dependencies.rb:343:in `new_constants_in'         from d:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/ active_suppo rt/dependencies.rb:496:in `require'         from ./test/unit/../test_helper.rb:3         from d:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb: 27:in `ge m_original_require'         from d:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb: 27:in `re quire'         from test/unit/user_test.rb:1

This is my first go a TDD, any help would be appreciated.