This is the ubuntu help site: http://www.ubuntu.com/getubuntu/releasenotes/904
These are the Vista requirements:
Home Basic
Home Premium / Business / Ultimate
1 GHz 32-bit (x86) or 64-bit (x64) processor
512 MB of system memory
20 GB hard drive with at least 15 GB of available space
Support for DirectX 9 graphics and 32 MB of graphics memory
DVD-ROM drive
Audio Output
Internet access (fees may apply)
Additional requirements
Actual requirements and product functionality may vary based on your system configuration. Windows Vista Upgrade Advisor can help you determine which features and edition of Windows Vista will run on your computer.
While all editions of Windows Vista can support multiple core CPUs, only Windows Vista Business, Ultimate, and Enterprise can support dual processors.
1 GHz 32-bit (x86) or 64-bit (x64) processor
1 GB of system memory
40 GB hard drive with at least 15 GB of available space
Support for DirectX 9 graphics with:
WDDM Driver
128 MB of graphics memory (minimum)
Pixel Shader 2.0 in hardware
32 bits per pixel
DVD-ROM drive
Audio Output
Internet access (fees may apply)
Additional requirements
Actual requirements and product functionality may vary based on your system configuration. Windows Vista Upgrade Advisor can help you determine which features and edition of Windows Vista will run on your computer.
While all editions of Windows Vista can support multiple core CPUs, only Windows Vista Business, Ultimate, and Enterprise can support dual processors.
Home Premium / Ultimate
TV tuner card required for TV functionality (compatible remote control optional).
Home Premium / Business / Ultimate
Windows Tablet and Touch Technology requires a Tablet PC or a touch screen.
Ultimate
Windows BitLocker Drive Encryption requires a USB Flash Drive and a system with a TPM 1.2 chip.