Hewlett-Packard, the world's largest personal computer maker, on Monday reported a better-than-expected 28 percent rise in quarterly profit as notebook PC sales increased.

The company also said its board authorized an $8 billion additional share buyback program.

Net income was $2.16 billion, or 81 cents per share, for its fiscal fourth quarter ended October 31, compared with $1.7 billion, or 60 cents per share, a year earlier.

Revenue grew 15 percent to $28.3 billion, compared with the average analyst forecast of $27.4 billion, according to Reuters Estimates.

HP reported earnings before certain items of 86 cents per share, beating the average Wall Street forecast of 82 cents.

Led by Chief Executive Mark Hurd, HP has cut costs and expanded high-profit businesses such as software and technology services. In July, it said it would buy Opsware Inc for $1.6 billion to bolster its business of helping companies manage computer systems.

The Palo Alto, California-based company forecast fiscal first-quarter earnings per share before items of 80 cents and revenue ranging from $27.4 billion to $27.5 billion. Analysts, on average, expect first-period earnings before items of 77 cents and revenue of $27.04 billion, according to Reuters Estimates.

For the full 2008 fiscal year, HP forecast earnings per share of $3.32 to $3.37 before items and revenue of about $111.5 billion. Analysts, on average, expect full-year earnings of $3.26 per share and revenue of $109.8 billion.

HP shares rose 1.5 percent in extended trading following the earnings report to $50.20, after closing down 2.6 percent at $49.44 on the New York Stock Exchange.

HP stock, up about 21 percent this year, trades at about 18 times estimated fiscal 2007 earnings per share compared with Dell Inc's multiple of 19 and International Business Machines Corp's 15.

(Reporting by Philipp Gollner; Editing by Braden Reddall)