Redmine

I am trying to install redmine on my Centos 5.10 box per http://www.redmine.org/projects/redmine/wiki/How_to_Install_Redmine_on_CentOS_%28Detailed%29

I went with:

ruby-2.0.0.p0.tar.gz (per the article)
    rubygems-1.4.2.tgz (per the article)
    redmine-2.5.0.tar.gz (instead of redmine-1.3.0.tar.gz)

When In "gem install bundler"

Successfully installed bundler-1.5.3
1 gem installed
Installing ri documentation for bundler-1.5.3...
ERROR: While executing gem ... (NoMethodError)
undefined method `map' for Gem::Specification:Class

when in "bundler install"

Fetching gem metadata from https://rubygems.org/.......
Fetching additional metadata from https://rubygems.org/..
Resolving dependencies...
Bundler could not find compatible versions for gem "i18n":
In Gemfile:
rails (= 3.2.17) ruby depends on
i18n (>= 0.6.4, ~> 0.6) ruby

i18n (0.4.2)

Could anyone help? Thank you