Windows Server 8 Beta (2012) | 3.34GB

I have included a PDF file from Microsoft's website for the System Requirements Overview.
System Requirements:

Windows Server “8” Beta Pre-installation Information
This software is intended for evaluation and deployment planning purposes only. If you plan to install the software on your primary computer, it is recommended that you back up your existing data prior to installation.
To use Windows Server “8” Beta, you need to be aware of the following system requirements*: Component System Requirement
• Minimum: 1.4 GHz 64bit processor Memory • Minimum: 512 MB RAM
Available Disk Space
• Minimum: 32 GB
Note: 32 GB should be considered an absolute minimum value for successful installation. Computers with more than 16 GB of RAM will require more disk space for paging, hibernation, and dump files. Drive DVD-ROM drive
Display and Peripherals
• Super VGA (800 x 600) or higher-resolution monitor • Keyboard • Microsoft Mouse or other compatible pointing device