From http://wiki.vtiger.com/archives

GA Release

• Exe Installer - Bundled with MySQL, Apache, PHP and vtiger CRM Source
• Bin Installer - Bundled with MySQL, Apache, PHP and vtiger CRM Source
• Source .tar.gz - vtiger CRM Source
• 5.0.x to 5.1.0 Patch

• Firefox plugin
• Outlook plugin
• Thunderbird plugin
• Customer Portal

Note:  vtiger CRM 5.0.4 office plugin continues to work with vtiger CRM 5.1.0.

RC Release

• Exe Installer - Bundled with MySQL, Apache, PHP and vtiger CRM Source
• Bin Installer - Bundled with MySQL, Apache, PHP and vtiger CRM Source
• Source .tar.gz - vtiger CRM Source
• 5.0.x to 5.1.0 Patch

• Firefox plugin
• Outlook plugin
• Thunderbird plugin
• Customer Portal

Note:  vtiger CRM 5.0.4 office plugin continues to work with vtiger CRM 5.1.0 RC.