The Windows 7 Beta download page is live, though it’s not linked from the official page yet. But, it’s not that easy to download yet. You have to go through a few fields that you need to complete and right now there is a very good chance you’ll get an error on one of them. You need a Live id, but the stress on the servers seems to be too big and it can’t be downloaded yet.
Try for yourself, and you’ll probably be able to download it in the next few days, once they beef up the servers a bit.
Windows 7 Requirements
- 1GHz processor (32- or 64-bit)
- 1GB of main memory
- 16GB of available disk space
- Support for DX9 graphics with 128MB of memory (for the Aero interface)
- A DVD-R/W drive

Update:
From the Microsoft Partner Program web site:
Partners with a MSDN or TechNet subscription can download Windows 7 Beta now. All other partners can download Windows 7 Beta starting January 9, 2009 at 12:00 P.M. Pacific Time.
Update 2:
ISO for Windows 7 Beta 32-bit (English):
7000.0.081212-1400_client_en-us_Ultimate-GB1CULFRE_EN_DVD.iso
ISO for Windows 7 Beta 64-bit (English):
7000.0.081212-1400_client_en-us_Ultimate-GB1CULXFRE_EN_DVD.ISO
no encuentro donde descargarlo