Ruby on Rails installation Help

I need help figuring out what I'm doing wrong.  I have Mac OS 10.5.8 and need to get ruby on rails installed and working.

g'em env' rom the terminal prompt has the following:


gem env
RubyGems Environment:
  - RUBYGEMS VERSION: 1.0.1 (1.0.1)
  - RUBY VERSION: 1.8.6 (2009-06-08 patchlevel 369) [universal-darwin9.0]
  - INSTALLATION DIRECTORY: /Library/Ruby/Gems/1.8
  - RUBYGEMS PREFIX: /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby
  - RUBY EXECUTABLE: /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby
  - RUBYGEMS PLATFORMS:
    - ruby
    - universal-darwin-9
  - GEM PATHS:
     - /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8
     - /Library/Ruby/Gems/1.8
  - GEM CONFIGURATION:
     - :update_sources => true
     - :verbose => true
     - :benchmark => false
     - :backtrace => false
     - :bulk_threshold => 1000
  - REMOTE SOURCES:
     - http://gems.rubyforge.org


I thought I had installed 1.9.3

When I try to install rubygems1.8.21 I get the following

rubygems-1.8.21 uriel$ sudo /usr/bin/ruby setup.rb
./lib/rubygems.rb:334: warning: parenthesize argument(s) for future version
./lib/rubygems.rb:516: warning: parenthesize argument(s) for future version
./lib/rubygems.rb:32:in `require': ./lib/rubygems/deprecate.rb:54: syntax error, unexpected ',', expecting '|' (SyntaxError)
... define_method name do |*args, &block| # TODO: really works ...
                              ^
./lib/rubygems/deprecate.rb:55: syntax error, unexpected tCONSTANT, expecting '}'
./lib/rubygems/deprecate.rb:64: syntax error, unexpected kEND, expecting '}'
./lib/rubygems/deprecate.rb:69: syntax error, unexpected kEND, expecting '}'
      from ./lib/rubygems.rb:32
      from setup.rb:27:in `require'
      from setup.rb:27


'which ruby'  from the terminal has
/usr/bin/ruby


Did I install ruby wrong?