Preorder windows 7 when its price is only £99, and happily received it yesterday (Have to travel 15 miles to pick it up local depot of CityLink though). I tried to install it on my iMac today, but as I expected, it has the same issue mentioned in my previous blog.

http://elian.co.uk/post/2009/05/11/Installing-VISTA-x64-on-iMac.aspx

Update:
I can confirm the old solution still works, just little note that, you need to disable UAC or use Run as administrator to install BootCamp drivers.