Opinion: Longhorn Vs. Linux... Again - OSNews.com:
"let's say that Longhorn will run comfortably on a 3.0 gHz processor and somewhat uncomfortably on a 2.5 or 2.7.
Businesses don't like to spend money. New computers cost money. Therefore it makes sense to try and make the computers you have work. Using ten year old software simply won't cut, in terms of interoperability and just plain productivity.
The obvious answer to that is linux. With a light window manager and good software it will more than suffice."