Another reference by the EE times - they (not PTSC, but EE times) came up with $200B.
http://www.eetimes.com/article/showArticle.jhtml?articleId=18309168
Reporters are usually highly inaccurate in their stories, hence not paid alot of money. $500B is more realistic ;-)
(Again, more Kudos to the Tucci page)
Regards