Microsoft have just released the consumer preview of Windows 8.
Windows 8 Consumer Preview works great on the same hardware that powers Windows 7:
Processor: 1 gigahertz (GHz) or faster
RAM: 1 gigabyte (GB) (32-bit) or 2 GB (64-bit)
Hard disk space: 16 GB (32-bit) or 20 GB (64-bit)
Graphics card: Microsoft DirectX 9 graphics device or higher
To use touch, you need a tablet or monitor that supports multitouch
To access Windows Store and to download and run apps, you need an active Internet connection and a screen resolution of at least 1024 x 768
To snap apps, you need a screen resolution of at least 1366 x 768
How to install Windows 8 Consumer Preview from an ISO image:
The easiest way to convert an ISO file to a DVD in Windows 7 is to use Windows Disc Image Burner. On a PC running Windows XP or Windows Vista, a third-party program is required to convert an ISO file into installable media—and DVD burning software often includes this capability. One option is the USB/DVD download tool provided by the Microsoft Store. You can also download Windows 8 Consumer Preview Setup, which includes tools that allow you to create a DVD or USB flash drive from an ISO file (Windows Vista or Windows 7 required)."