Thanks for wanting to use Vagrant! Unfortunately, this is not the way to install Vagrant anymore. We now make installers for the various operating systems Vagrant supports.
Vagrant is no longer distributed as a RubyGem. Please download the latest version for your operating system from the URL below. If you still wish to use the RubyGem version, you can manually install version 1.0.7. Note that the RubyGem version hasn't been updated in over a year and will no longer receive any updates.
Prior to installing Vagrant using the installer, make sure you uninstall all your Vagrant gems, since they sometimes conflict.
If you want to learn more about why we don't distribute using RubyGems anymore, please read this: mitchellh.com/abandoning-rubygems