CHICAGO--(BUSINESS WIRE)--Intel's negative pre-announcement this morning suggests the end of support for Windows XP was a more significant factor than previously estimated in last year's perceived stabilizing personal computer (PC) demand, according to Fitch Ratings. Consequently, extended PC refresh cycles may result in a resumption of negative PC sales growth. Intel Thursday changed its first-quarter revenue outlook as a function of weaker than expected PC demand. Intel now expects $12.8 bill