It is the full version ... it's just a time based trial, you want Microsoft to deactivate the Timer for it then you have to pay what you'd pay for Windows XP Home.
But as I've said 360days free windows and a new one will replace that so technically free.
It's not a Beta, it's not something you can't actually buy if you wanted to, it's just a free version for those who've just spend like £350 on an Athlon64 and actually want it to run perfectly.
I know you can't actually get to the order page cause you need to go in from a secure location, and for that you need the history

but it was just to show you that it is available and is free.
Has been for atleast the past year, even when everyone was telling me 'Oh Windows XP 64bit is ONLY for the Itanium Processors, Blah blah blah'
If you haven't got an Athlon64 then it's worthless, if you have then it's priceless.