Sucsessful Forum Post From Windows 7 Answered
I am not sure if this is the first, but Instuctables has been viewed using Windows 7!
For anyone not aware, the Windows 7 beta is free to download for the first 2.5 million visitors, and last I checked it was still available.
This is a link to the download site.
UPDATE: Microsoft has lifted the 2.5 million download limit and it will be available until January 24th Cnet Article