Ubuntu GNU/Linux 14.04 LTS x64 Long term support version of the famous free and open source OS. 64bit version.

System requirements:

• x64 capable CPU
• 700 MHz processor
• 512 MiB RAM
• 5 GB of hard-drive space
• VGA capable of 1024x768 screen resolution
• Either a CD/DVD drive or a USB port for the installer media
• (Internet access is helpful)

Installation guide:

• Burn the ISO to DVD or use the Pendrive Linux program to create a startup flash drive (Startup Disk Creator - if you use Ubuntu).
• In the BIOS settings of your PC, select DVD drive / USB flash drive (respectively) as your First Boot Device.
• Follow the instructions of Ubuntu installer.
• When the PC restarts during installation - log on to BIOS (DEL key, or F2 or other button), and select your Hard Drive as the First Boot Device.
• The installation will continue and you will log on to your Ubuntu desktop.

Notes:

• Ubuntu LTS version will be supported for 5 years (until April 2019).
• Even though you can see the name 'amd64', the OS will work on any x86_64 CPU, both Intel or AMD.

Enjoy!