If you check the link in that story http://www.maximumpc.com/article/new...%99s_installed
and read some of the comments you will see a link to Harold Wong's blog who works for Microsoft
If you scroll down to some of the comments he made to people you will see this...
"Ok, I'll do my best to address all the comments to date.
1. Joel: I am very happy with the Windows Easy Transfer Tool. This works great for the home or one off computer. I used this tool to move stuff from Windows Vista to Windows 7 Beta as well as from Windows 7 Beta to Windows 7 RC. I used my USB Hard Drive as the storage location.
2. Todd: If you purchased the Windows 7 Upgrade, you only need the original media (CD / DVD) of Windows XP or Windows Vista. The Upgrade media will ask you to insert the media from XP or Vista so it can perform a check of the physical media before proceeding. Of course, if you already have Windows Vista installed on the machine, it will just allow you to perform an in-place upgrade.
3. Jeff: I guess I should have been a bit more clear on my stance and situation. For my personal computers at home, I NEVER do in-place upgrades. I always transfer the data off and wipe and reload. When testing beta Operating Systems, I absolutely NEVER attempt an in-place upgrade to final code. This is true for home and business. In a business environment, there are a lot more things that need to be considered. If the user desktops are not well controlled and users can install whatever they want, then in-place upgrades are usually not a good option for me because there's too great of a chance that the user has "messed up" enough items that it is probably time to do a clean up anyways. If the environment is large enough, I would have created images to deploy to desktops. In this case, I would still not do upgrades as I would create new images and deploy using those.
4. Chris: I agree with you in that I would never install beta software on mission critical systems. I use beta to test functionality and capabilities.
Further down he said this
"From what I understand, the Upgrade check will require the OS Installation media - the Recovery Disk will not work.
I'm sure if you are enterprising enough to do searches on the Internet, you can find some interesting workarounds to get Windows Vista Upgrade installed without the original media. Who knows if this will work for Windows 7.
So he isn't ruling out the Windows Vista workaround.