If you want to download the just-released Windows 7 Beta, you'll need a TechNet Plus subscription. And, if you are not a TechNet Plus subscriber, you can get one for 15% off using the discount code: TMSAM12.
To order a TechNet subscription, go here:
I recommend the TechNet Plus DIRECT subscription - that way you can download it today, rather than wait for the DVD's to arrive in the mail in a few weeks. The product keys you'll need to activate you Beta software are available through the web site as well.
Don't forget to use code: TMSAM12