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Tuesday, that changed. HP reported a 51% jump in quarterly net income just nine days after Dell warned that its results would disappoint.

HP's sales of PCs, printers and servers all rose in the quarter ended April 30. That allowed the company to post net income of $1.5 billion, or 51 cents a share, up from $1 billion, or 33 cents a share, a year ago.

Revenue of $22.6 billion rose 5% from $21.6 billion a year ago.

Tech analysts say much of the gains came at the expense of No. 1 PC maker Dell. HP's share of the worldwide PC market grew in the quarter, while Dell's slipped, researcher Gartner says. HP shares have risen 48% in the past year. Dell's are down 40%.

"HP has made huge strides in improving its business. They've become a competitor to Dell again," says Gartner tech analyst Martin Reynolds.

Dell used to be the company so infallible it was known as "Teflon Dell." It continually posted record revenue while HP floundered. In 2005, HP's board ousted CEO Carly Fiorina, and replacement Mark Hurd has reorganized the company, slashed costs and laid off thousands of workers.

Now Hurd's overhaul seems to be righting HP. "The cost savings and the reorganization are kicking in," says equity analyst Shaw Wu with American Technology Research.

But HP may also be benefiting from changes in the PC industry that reduce some of Dell's longtime advantages, says tech analyst Roger Kay with Endpoint Technologies Associates. Among them:

•International growth. Dell dominates the U.S. market, making about one out of every three PCs sold here. But the U.S. market is maturing and not growing as fast as it used to. The real opportunity is in developing countries such as India and China, where many people don't yet have PCs.

But Dell has struggled in many international markets, Kay says. Dell PCs are typically sold over the Internet and paid for with credit cards. That's tough in areas where online commerce is new or not trusted, Kay says. HP, in contrast, sells mainly through stores.

Dell spokesman Jess Blackburn says international businesses are very willing to buy online, even if consumers are reluctant.

Dell's sales outside the USA, Canada and Latin America accounted for 35% of its revenue in its most recent fiscal year. More than 60% of HP's revenue came from outside the USA. (The companies differ slightly on how they report geographic data.)

•Soaring laptop sales. In May 2005, the number of laptops sold in U.S. retail stores outpaced the number of desktops for the first time, researcher Current Analysis says. Unfortunately for Dell, it's tougher to sell laptops online than desktops, says Current Analysis PC analyst Samir Bhavnani. Because weight and size are crucial laptop features, many customers want to go to a store and physically pick them up before buying, Bhavnani says.

Blackburn says customers are savvy enough to buy laptops online. But HP appears to be benefiting from the shift. Its laptop revenue jumped 27% in the quarter from a year ago.

•Fewer speeds and feeds. PC makers have traditionally touted their products by advertising how fast their processors are and how many features they have. That was important when PCs were slow. But today, even a low-end PC can easily handle e-mail, Web surfing and other normal consumer tasks.

Shoppers are now looking for other attributes, such as PCs that are attractive and easy to use, Bhavnani says. Apple, which launched a new line of laptops Tuesday, is known for this, he says. HP is making a play too, through a new advertising campaign that emphasizes the usefulness of its products.

But Dell hasn't made that switch, Bhavnani says. "Dell is focused on selling products, while the competition is increasingly focused on selling a lifestyle," he says.

•Streamlined supply chain. Dell makes most of its PCs to order and can change prices on its website instantly. For years, that has allowed it to adapt quickly to changes in component prices — and keep costs much lower than competitors with huge backlogs of products in retail stores.

But HP and others have learned from Dell, Gartner's Reynolds says. The operating profit in HP's PC group was 3.6% in the quarter, up from 2.3% a year ago.

Blackburn says Dell will overcome its challenges. The company has promised to some day reach $80 billion in annual revenue. That would make it almost as large as HP. (HP is bigger than Dell overall because it sells products that Dell does not, including very large servers and business-consulting services.) "We feel very strongly that Dell's business model, and our ability to work directly with our customers, still gives us an advantage," Blackburn says.

HP has no intention of letting Dell off easy. CEO Hurd says he plans to hire hundreds of sales reps to target big companies, for example. Large firms are Dell's biggest market.

But Hurd insists his company isn't focused on beating its rival. "Our sole objective isn't to just gain share," he said. "It's to run a good business."

More detail on Dell's business will be released Thursday, when it reports quarterly earnings.