Dê uma olhada:
https://wiki.ubuntu.com/DesktopExperienceTeam/UnityHardwareRequirements
]
po entao meu pc n vai rodar 1gb de ram só e processador celeron
Nessa mesma configuração eu rodo o ubuntu
-Computer-
Processor : AMD Sempron(tm) Processor 2800+
Memory : 991MB (439MB used)
Operating System : Ubuntu 11.04 (Natty)
User Name : paulo (Paulo Corrêa)
Date/Time : Sáb 04 Jun 2011 14:08:31 BRT
-Display-
Resolution : 1024x768 pixels
OpenGL Renderer : Software Rasterizer
X11 Vendor : The X.Org Foundation
-Multimedia-
Audio Adapter : ICH - SiS SI7012
-Input Devices-
Power Button
Power Button
AT Translated Set 2 keyboard
ImPS/2 Generic Wheel Mouse
-Printers (CUPS)-
Photosmart-C4200-series : <i>Default</i>
-SCSI Disks-
ATA SAMSUNG SP0842N
HL-DT-ST DVD-RAM GSA-H20N