anyone with windows xp/vista/7 can get the full version for $40. you'll get the "PRO" version, and it's required, there's no way to get the standard version or "enterprise" version.
Only techNet subscribers get to download ISO versions of Win8, for the time being.
And the windows 7 USB-DVD tool allows users to burn the Win8 image with a bootup option format-media.
anyone that purchased a Windows 7 machine in a past 4 months or so can get windows 8 pro for $15 with a promo code on the check out of the upgrade option.
retail standard price for standard 8 is $100. Pro is $200. Enterprise, server, etc.
just use the upgrade option from Microsoft.com on your xp/vista/7 computer, 32-bit or 64-bit.
you'll be prompted to download a verification tool. once the current OS is verified, you'll be prompted to move forward with a multi-gigabyte download after you pay for it, $40 bucks over credit card or paypal (paypal is way-way faster).
after you receive the serial key and the download, the same dialogue program initiates a request of a USB drive or "other" media, to put the entire win8 Pro OS with format-boot. the upgrade-move option doesn't force anyone to use old files or transfers. however, only vista and 7 users will be allowed the upgrade-move, as far as transferring files and certain software over. XP users will be forced to reformat the system. anyone with vista and 7 can also move forward with a reformat or dual boot.
but keep in mind also; xp users that are using multi-boot options with 7 and vista on their system, 8 will take over and still offer dual-multi-boot options, nothing changes. in summary of that, the xp/vista/7 upgrade options
otherwise the install options from a the boot-format drive have the exact same interface as the windows 7 install, offering "custom" or "upgrade" - you can either put windows 8 on another drive/partition and have a dual boot, or you can wipe the current operating systems on the same computer (whatever is detected) and run a dual-multi boot. once the windows 8 install finishes, put in the serial key, and you are set to go.
the promotion will go on until 2012 finishes, or 2013 January.
windows 8 standard does not come with the media center. current windows 8 machines that are not PRO, will cost $69 to upgrade to 8 with media center.
currently, windows 8 "pro" machines can receive media free with a promo code through Microsoft.com.
...basically, anyone that just bought this from amazon is getting reeled in the wrong way. get it directly from Microsoft.com if you already have xp/vista/7. save yourself the hassle of being forced to spend $30 on amazon later on and having to physically wait for the actual product.