The world's biggest software company, Microsoft, has experienced its first drop in revenue since it went public in 1986 as the global recession wounds its seemingly indestructible sales of computer operating systems.  Microsoft tonight revealed revenue of $13.65 billion for the three months to March, a 6 percent decline on the same period last year. Hit by write-downs of $420 million in investments and severance charges of $290 million, profit has dropped by 32 percent to $2.98 billion.

