Você precisa de uma resolução mínima de 1024x768
Aqui estão os Requisitos do Sistema do Ubuntu 12.04
Minimum
Precise Pangolin (12.04.3 32-bit)
384 MB of RAM
700 MHz processor (about Intel Celeron or better)
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
Precise Pangolin (12.04.3 64-bit)
1 GB of RAM
Dual Core processor
10 GB of hard-drive space or SSD (the more hard disk capacity, the better)
Any graphics card with OpenGL 1.4 support (All GPUs released today by either NVidia, AMD or Intel; GPUs released by NVidia and AMD over the last 5 years; GPUs released by Intel after the GMA 950)
Either a CD/DVD drive or a USB port for the installer media
Internet access is helpful