A new PC running Windows XP that carries the Windows Vista Capable PC logo can run Windows Vista. All editions of Windows Vista will deliver core experiences such as innovations in organizing and finding information, security, and reliability. All Windows Vista Capable PCs will run these core experiences at a minimum. Some features available in the premium editions of Windows Vista—like the new Windows Aero user experience—may require advanced or additional hardware.
A Windows Vista Capable PC includes at least:
A modern processor (at least 800MHz)
512 MB of system memory.
A graphics processor that is DirectX 9 capable
Windows Vista Premium Ready PCs
Some Windows Vista Capable PCs have been designated Premium Ready. These PCs will provide an even better Windows Vista experience, including the Windows Aero user experience. Features available in specific premium editions of Windows Vista, such as the ability to watch and record live TV, may require additional hardware.
A Windows Vista Premium Ready PC includes at least:
1 GHz 32-bit (x86) or 64-bit (x64) processor).
1 GB of system memory.
Support for DirectX 9 graphics with a WDDM driver, 128 MB of graphics memory (minimum), Pixel Shader 2.0 and 32 bits per pixel.
40 GB of hard drive capacity with 15 GB free space.
DVD-ROM Drive.
Audio output capability.
Internet access capability.
Can the Windows Vista experience vary on different PCs?
Yes. Windows Vista is the first Windows operating system with a user experience that adapts to take advantage of the capabilities of the hardware on which it is installed.
All Windows Vista Capable PCs will be able to run at least the core experiences of Windows Vista.
All Windows Vista Premium Ready PCs can deliver even better Windows Vista experiences, including the new Windows Aero user experience.
Does buying a Windows Vista Capable PC mean that I will receive a free upgrade to Windows Vista?
No. A PC that is Windows Vista Capable or Premium Ready means that the PC is ready for an upgrade from Windows XP. You would still need to purchase the edition of Windows Vista that you want to install on your Windows Vista Capable or Premium Ready PC.
Vista Advisor Tool
Microsoft have released a Windows Vista Advice Memory Advisor tool which will let you know about software and hardware complications you might encounter. It check whether your system meets the requirements.
Follow the above link and download the tool to check your pc!