Olá, pessoal.

Para facilitar, ainda mais para a galera, juntei os links para download das versões mais recentes do Ubuntu (em ordem crescente).

Obs.: lembrando que muitas destas versões não possuem mais suporte.

Ubuntu 8.04.4 LTS (Hardy Heron)

Desktop:

• 32 bits: ubuntu-8.04.4-desktop-i386.iso
• 64 bits: ubuntu-8.04.4-desktop-amd64.iso

Server:

• 32 bits: ubuntu-8.04.4-server-i386.iso
• 64 bits: ubuntu-8.04.4-server-amd64.iso

Ubuntu 8.10 (Intrepid Ibex)

Desktop:

• 32 bits: ubuntu-8.10-desktop-i386.iso
• 64 bits: intrepid/ubuntu-8.10-desktop-amd64.iso

Server:

• 32 bits: intrepid/ubuntu-8.10-server-i386.iso
• 64 bits: intrepid/ubuntu-8.10-server-amd64.iso

Ubuntu 9.04 (Jaunty Jackalope)

Desktop:

• 32 bits: ubuntu-9.04-desktop-i386.iso
• 64 bits: ubuntu-9.04-desktop-amd64.iso

Server:

• 32 bits: ubuntu-9.04-server-i386.iso
• 64 bits: ubuntu-9.04-server-amd64.iso

Ubuntu 9.10 (Karmic Koala)

Desktop:

• 32 bits: ubuntu-9.10-desktop-i386.iso
• 64 bits: ubuntu-9.10-desktop-amd64.iso

Server:

• 32 bits: ubuntu-9.10-server-i386.iso
• 64 bits: ubuntu-9.10-server-amd64.iso

Ubuntu 10.04.4 LTS (Lucid Lynx)

Desktop:

• 32 bits: ubuntu-10.04-desktop-i386.iso
• 64 bits: ubuntu-10.04-desktop-amd64.iso

Server:

• 32 bits: ubuntu-10.04-server-i386.iso
• 64 bits: ubuntu-10.04-server-amd64.iso

Ubuntu 10.10 (Maverick Meerkat)

Desktop:

• 32 bits: ubuntu-10.10-desktop-i386.iso
• 64 bits: ubuntu-10.10-desktop-amd64.iso

Server:

• 32 bits: ubuntu-10.10-server-i386.iso
• 64 bits: ubuntu-10.10-server-amd64.iso

Ubuntu 11.04 (Natty Narwhal)

Desktop:

• 32 bits: ubuntu-11.04-desktop-i386.iso
• 64 bits: ubuntu-11.04-desktop-amd64.iso

Server:

• 32 bits: ubuntu-11.04-server-i386.iso
• 64 bits: ubuntu-11.04-server-amd64.iso

Ubuntu 11.10 (Oneiric Ocelot)

Desktop:

• 32 bits: ubuntu-11.10-desktop-i386.iso
• 64 bits: ubuntu-11.10-desktop-amd64.iso

Server:

• 32 bits: ubuntu-11.10-server-i386.iso
• 64 bits: ubuntu-11.10-server-amd64.iso

Ubuntu 12.04.3 LTS (Precise Pangolin)

Desktop:

• 32 bits: ubuntu-12.04.3-desktop-i386.iso
• 64 bits: ubuntu-12.04.3-desktop-amd64.iso

Server:

• 32 bits: ubuntu-12.04.3-server-i386.iso
• 64 bits: ubuntu-12.04.3-server-amd64.iso

Ubuntu 12.10 (Quantal Quetzal)

Desktop:

• 32 bits: ubuntu-12.10-desktop-i386.iso
• 64 bits: ubuntu-12.10-desktop-amd64.iso

Server:

• 32 bits: ubuntu-12.10-server-i386.iso
• 64 bits: ubuntu-12.10-server-amd64.iso

Ubuntu 13.10 (Saucy Salamander)

Desktop:

• 32 bits: ubuntu-13.10-desktop-i386.iso
• 64 bits: ubuntu-13.10-desktop-amd64.iso

Server:

• 32 bits: ubuntu-13.10-server-i386.iso
• 64 bits: ubuntu-13.10-server-amd64.iso

Ubuntu 13.04 (Raring Ringtail)

Desktop:

• 32 bits: ubuntu-13.04-desktop-i386.iso
• 64 bits: ubuntu-13.04-desktop-amd64.iso

Server:

• 32 bits: ubuntu-13.04-server-i386.iso
• 64 bits: ubuntu-13.04-server-amd64.iso

Divulguei a lista em meu blog, também: Blog Linux Saudável: Download Ubuntu - Diversas Versões

Abraços.