Oct. 27 2012, before buying Windows 8 Pro 64 Bit online for (was it really $39.99?) in Bootcamped Windows 7 Pro 64 Bit, it ran an upgrade compatibility test which turned out OK so paid for and downloaded W. 8 Pro ISO.
I then shrunk 500GB bootcamped Windows 7 drive space in half and booted the Windows 8 ISO DVD formatting NTFS to the 250GB shrink. Not an update, this was a new/clean insatall.
While there are other ways to do it, I retained Windows 7 for fallback which has proven to be unnecessary but there is a lot of data there that is available to, used by W 8.
When Apple comes out with support for Windows 8 bootcamp....................................................................... ............................................... I will save for restore data & clear the 500GB, then reinstall W 8 to it.
Windows 8 for Mac & PC having Metro, is the best OS I have ever seen. Well, Mac Pro is not so portable as would be an iPad or iPhone, but it has all the apps you might want freely via metro side of the OS.
Microsoft deserves a whole lot of credit for what they have done here. The Windows 8 Cost is right now less than1/2 of the taxes I paid to get an $886 with case, screen protect, iPad 3 in Canada.
With W 8 and a 27" screen which I do not have to hold in my hands, like an iPod, iPad, iPhone, Windows 8 removes the limitation / constraints inherent in small handhelds which, who knows, may be found to be unhealthy close to one's face or brain whichever comes first. You can compare 10" Book reading to 27" where a black background can be set.
There is a lot I don't know that you might find from other response to this posting.