I think you've been misled. There are so many reasons that no matter what you try you'll never get Windows 7, assuming you mean the desktop Windows 7, running on the Eris. I doubt if you could get Windows Phone 7 running on the Eris, either. AFAIK, there's never been any version of Windows 7 compiled for ARM processors, only for x86 and x86-64. Even if it were, the hardware constraints of the Eris would be completely ludicrous to expect it to run a huge Windows 7 installation, even if the ROM actually ran from the SD card, which would be the only way it would fit since the internal flash memory of the Eris is too small.
I did a quick Google search and I couldn't easily find the article you mention. Do you have a link?