The Windows 7 team has announced the deadline to download of Windows 7 Beta as Februrary 10. If you begin download by then, the download needs to be completed by February 13.
The end of the Beta for Windows 7 was announced in a blog entry by the team, General availability for the Windows 7 Beta to end. MSDN and TechNet Subscribers will continue to have access to the Windows 7 Beta bits throughout the Windows 7 Beta phase.
You can also get access to Windows 7 Beta through the Windows 7 Beta Customer Preview Program (CPP). You can learn more about Windows 7 Beta and get support through Springboard. You can follow updates about Windows 7 on the Windows 7 team blog.