Avast home edition on Windows 7 x64 (64bit)

Hello, I’ve a problem with my Avast Home edition and Windows 7 64 bit.
This is Avast can’t do the scan on startup because of the version of my Windows 7. The message says something like “not compatible with 64 bit”.
¿What can I do? ¿is possible in a short tieme a 64 bit version?
Thank you.

Right now, you need to wait for version 5.1.
64 bits boot scan is not available yet.