Hello Frogger21,
The ONLY legitimate place for a retail purchaser to buy a genuine electronically delivered product key and product download for Microsoft Windows is Microsoft itself thru its digital distribution partner Digital River and the Microsoft Store (http://store.microsoft.com).
Recently Microsoft has entered into an agreement with Dell to allow Dell to sell and electronically deliver Microsoft product keys and product downloads. As of this writing, AFAIK Dell has started to sell Office 2010 in this manner and is likely to
expand to other Microsoft products including Windows. It's alos likely that other major players will be authorized by Microsoft to do the same.
To answer your question, I do NOT believe that the seller you linked above is a legitimate source for genuine Microsoft products.
Buy Office 2007 Now, Get Office 2010 Free http://office2010.microsoft.com/en-us/tech-guarantee/microsoft-office-2010-technology-guarantee-FX101825695.aspx?CTT=97