While the Microsoft servers continue to struggle with the massive amount of traffic, there might just be a solution for you: direct download links for both the 32 and 64 bit ISO images.
Windows 7 Beta (x86) : 7000.0.081212-1400_client_en-us_Ultimate-GB1CULFRE_EN_DVD.ISO
Windows 7 Beta (x64) : 7000.0.081212-1400_client_en-us_Ultimate-GB1CULXFRE_EN_DVD.ISO
See if you have luck with the direct links. Currently it's working for me, and fairly fast as well – about 340kb/s.
You'll still need to go back for a key, assuming you want to use the beta for more than 30 days, but at least you'll be able to burn a DVD or mount the ISO in your favorite virtualization app. Alternatively, there are plenty of timer reset and watermark removal tools available on the various torrent trackers.