The procedure on that site activates an OEM copy, I did the same sort of thing with XP when it came out in 2001, and it work great for about a year until they released the first service pack.
From the looks of it though, the release on that site would work permanently even after the retail release comes out. I personally can't try it because I would get my MCSA yanked from Microsoft if I got caught 'playing' with licensing like that. But if you don't have that sort of personal restriction I'd say it looks very workable.
