http://blog.seattlepi.com/microsoft/archives/201302.asp

If there was any doubt over Microsoft's influence in Washington state, consider the findings of a new University of Washington study: The software titan accounted for 13.6 percent of the gross state product here in 2008.
The UW study – aptly titled "The Microsoft Economic Impact Study" – was commissioned by Microsoft but was based mostly on government data. In the four years since a similar study was published with 2004 figures, Microsoft's local employment grew by 11,000.
it is recommended that the findings of this study be filtered with this book:

http://www.amazon.com/How-Lie-Statistics-Darrell-Huff/dp/0393310728

i think this line is the most telling:

The average local Microsoft employee made $152,212 in 2008 – $178,159 if you include stock options. (The average aerospace worker made $87,113 in wages.)
talk about skewing the study; one can parse the above fact 2 ways: either they are averaging everyone's salaries together, the high paid executives and the peons, which means that most of the money ended up in the hands of a select wealthy few or the 152 grand a year figure is an accurate representation of the average microsoft employee's salary which means that the money ended up in the hands of the top 10 percent of earners in the state or put another way it ended up in the hands of a slightly bigger portion of select wealthy few and thus means little to the average joe six pack living in washington.

the reality is that no matter which way you spin the "facts" in this report, at the end of the day it is little more than "trickle down" theory in action, even if we assume that every single "fact" is true and accurate, most of the money generated still ended up in the savings accounts of a select few, with a relatively small percentage of the dough actually put back into the economy and in the hands of the average man.

now don't get me wrong, i'm not saying that microsoft (and companies like it) don't play a vital role in the economy of states where they reside but their economic impact is grossly over-stated, the reality of the matter is that if microsoft layed off all it's employees in washington state tomorrow, the people that would be lefty without a job are people that were averaging 152 grand a year and most likely have very fat bank accounts and can easily survive being without a job for the next couple of years, if not longer. they could continue spending as they did before and microsoft's departure wouldn't really have any significant impact until maybe a decade from now.