Microsoft said on Thursday that its second-quarter profits jumped 79 percent on strong sales of its flash-ship Windows operating-system.

The Redmond Wash.-based software maker said its profit increased to $4.71 billion, or 50 cents per share, from $2.63 billion, or 26 cents per share in the same period last year.

Analysts polled by Thomson Financial had forecast a profit of 46 cents per share.

Revenue rose 31 percent to $16.37 billion from $12.5 billion in the year-ago quarter, ahead of analysts' prediction of $15.95 billion in sales.

Microsoft's client division, responsible for Vista, posted revenue of $4.34 billion. The business division, which includes Office, brought in $4.81 billion in sales.

Stronger-than-expected PC sales in the second quarter - 13.1 percent compared with last year, according to research group Gartner Inc. - helped both divisions.

Microsoft