64bit Programming and Assembly Issues
 

I have found this book is very usefull :)

The 64-Bit technology introduces several new and and complex tasks for
software-developers. Even that the hardware developing industry claims
that future software development should take care about the new introduced
compiler systems, it is necessary to have a deep inside view on how the
new underlaying 64-Bit assembly language works. This paper describes what
64-Bit means for future software developments, how 64-Bit influences assembly
programming and how to port applications programmed under 32-Bit to 64-Bit.
It is heavy based on the IA architecture and the Windows(R) operating system.

http://tuts4you.com/download.php?view.243

Old stuff ;) you will find a lot of documentation more interesting directly on intel website.