Hewlett-Packard Co cut its full-year profit outlook after quarterly revenue missed expectations on weak sales of printers, personal computers and servers, sending its shares down 3 percent.

While HP's diversified business lines -- which also include computer services and software -- have kept it relatively resilient to the economic downturn, it is still vulnerable to sharp cutbacks in corporate spending on technology.

The big disappointment, not surprisingly, is the shortfall in revenue, said Pacific Crest Securities analyst Brent Bracelin. Their hardware businesses, both servers and storage, are under intense scrutiny. Budgets are being cut and that showed up in the shortfall today.

For fiscal 2009, HP on Wednesday forecast profit excluding items of $3.76 to $3.88 a share, on a revenue decline of 2 to 5 percent from $118.4 billion in fiscal 2008. That compared with its previous forecast for earnings per share of $3.88 to $4.03 on revenue of $127.5 billion to $130 billion.

Wall Street analysts, on average, had expected earnings of $3.78 a share on revenue of $126.6 billion.

They are vulnerable to weakening PC sales, said Shebly Seyrafi, analyst at Calyon Securities. Shares are down on a combination of the actual results, the revenue mess and the lowering of the annual guidance. There are lots of reasons to be concerned about Hewlett-Packard.

The technology bellwether said net profit for its fiscal first quarter ended January 31 fell to $1.85 billion, or 75 cents a share, from $2.13 billion, or 80 cents a share, in the year-ago period.

Excluding items, HP earned 93 cents a share, matching average analyst estimates, according to Reuters Estimates. Analysts pointed to tight cost controls.

A laser focus on cost-control has benefited HP despite a dramatic falloff in revenues and I don't think the outlook is as bad as it could have been given currency headwinds and overall weak demand environment, said Bill Kreher, analyst at Edward Jones.

HP said fiscal first-quarter revenue rose 1 percent to $28.8 billion, below the $31.9 billion Wall Street estimate.

For the current quarter, HP expects a profit of 84 cents to 86 cents a share from continuing operations, on a revenue decline of 2 to 3 percent from a year ago. That compares with the average Wall Street forecast for earnings of 90 cents a share on revenue of $31 billion.

The company is the world's No. 1 PC maker, with a market share of nearly 20 percent in the 2008 fourth quarter, according to IDC.

Last year, HP acquired Electronic Data Systems Corp in a $13.2 billion deal, making HP the second largest technology services company behind International Business Machines Corp .

Shares of HP, a Dow component, are down around 20 percent from a year ago. The stock fell to $32.93 in extended trading from its New York Stock Exchange close of $34.08.

(Reporting by Gabriel Madway; editing by Richard Chang)