Update: If you are ready to remove Windows 7, feel free to read out How to remove or ‘uninstall’ Windows 7 guide  to help you on your way.
Title says it all:
Due to an enormous surge in demand, the download experience was not ideal so we listened and took the necessary steps to ensure a good experience. We have clearly heard that many of you want to check out the Windows 7 Beta and, as a result, we have decided remove the initial 2.5 million limit on the public beta for the next two weeks (thru January 24th). During that time you will have access to the beta even if the download number exceeds the 2.5 million unit limit.
Windows 7 Blog 
Microsoft totally dropped on the ball on Window 7 Beta’s release and it is nice that they are trying to make up for it. At least no more fighting for product keys. :D