installing ruby

Cannot complete the install because of a conflicting dependency.
  Software being installed: Dynamic Languages Toolkit - Ruby Development Tools 2.0.0.v20100505-1154-7G--E_EkMU3NHhvAUo0G (org.eclipse.dltk.ruby.feature.group 2.0.0.v20100505-1154-7G--E_EkMU3NHhvAUo0G)
  Software currently installed: PDT Mylyn Feature 3.1.1.201209121312 (org.eclipse.php.mylyn.feature.group 3.1.1.201209121312)
  Only one of the following can be installed at once:
    Dynamic Languages Toolkit Debug UI 2.0.0.v20100115-2213 (org.eclipse.dltk.debug.ui 2.0.0.v20100115-2213)
    Dynamic Languages Toolkit Debug UI (Incubation) 0.95.1.v20080903-1434 (org.eclipse.dltk.debug.ui 0.95.1.v20080903-1434)
    Dynamic Languages Toolkit Debug UI 4.0.0.201206120848 (org.eclipse.dltk.debug.ui 4.0.0.201206120848)
    Dynamic Languages Toolkit Debug UI 1.0.0.v20090610-1638 (org.eclipse.dltk.debug.ui 1.0.0.v20090610-1638)
    Dynamic Languages Toolkit Debug UI (Incubation) 0.95.0.v20080611-1825 (org.eclipse.dltk.debug.ui 0.95.0.v20080611-1825)
    Dynamic Languages Toolkit Debug UI (Incubation) 0.9.0.v20070621 (org.eclipse.dltk.debug.ui 0.9.0.v20070621)
  Cannot satisfy dependency:
    From: Dynamic Languages Toolkit - Core Frameworks 2.0.0.v20100518-1923-7L--EAAoOVMSMc4AWEvJ (org.eclipse.dltk.core.feature.group 2.0.0.v20100518-1923-7L--EAAoOVMSMc4AWEvJ)
    To: org.eclipse.dltk.debug.ui [2.0.0.v20100115-2213]
  Cannot satisfy dependency:
    From: Mylyn DLTK Bridge 4.0.0.201206120848 (org.eclipse.dltk.mylyn 4.0.0.201206120848)
    To: bundle org.eclipse.dltk.debug.ui 4.0.0
  Cannot satisfy dependency:
    From: Dynamic Languages Toolkit - Mylyn Integration 4.0.0.201206120848 (org.eclipse.dltk.mylyn.feature.group 4.0.0.201206120848)
    To: org.eclipse.dltk.mylyn [4.0.0.201206120848]
  Cannot satisfy dependency:
    From: Dynamic Languages Toolkit - Ruby Development Tools 2.0.0.v20100505-1154-7G--E_EkMU3NHhvAUo0G (org.eclipse.dltk.ruby.feature.group 2.0.0.v20100505-1154-7G--E_EkMU3NHhvAUo0G)
    To: org.eclipse.dltk.core.feature.group [2.0.0,3.0.0)
  Cannot satisfy dependency:
    From: PDT Mylyn Feature 3.1.1.201209121312 (org.eclipse.php.mylyn.feature.group 3.1.1.201209121312)
    To: org.eclipse.dltk.mylyn.feature.group 3.0.0