Windows 7 is the next release of the Windows client operating system, built on the secure foundation of Windows Vista and Windows Server 2008.
Processor: 1 GHz 32-bit or 64-bit processor
Memory: 1 GB of system memory
Hard drive: 16 GB of available disk space
Video card: Support for DirectX 9 graphics with 128MB memory (in order to enable Aero theme)
Drive: DVD-R/W drive
Internet connection (to download the Beta and get updates)
Windows 7 Beta Frequently Asked Questions: http://www.microsoft.com/windows/windows-7/beta-faq.aspx