NEW YORK (CNNMoney.com) - Computer makers enjoyed strong year-over-year growth during the first calendar quarter this year, according to new U.S. retail sales data.

But while that strong growth may imply that computer manufacturers are on track to continue that growth the rest of the year, it remains to be seen whether Microsoft's (Research) delay of the consumer version of its highly anticipated Windows Vista operating system will derail that growth, analysts say.

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Number two PC maker Hewlett Packard sold about 605,000 PCs at U.S. retail outlets in the first quarter, according to industry researcher Current Analysis. That's a 28.5 percent increase from the previous year's calendar quarter.

The Current Analysis figures apply to U.S. retail sales only and do not include international sales or sales from the Internet or other non-resale stores. Because of those constraints, the data do not include sales from Dell, the number one computer maker, because of its direct sales model.

"There is a lot of positive growth in the first quarter, but since the marketing plans of all these manufacturers were tied into Vista, they need to revisit these plans," said Samir Bhavnani, principal analyst in the mobile computing and electronics group at Current Analysis.

PC makers such as Compaq are billing their current products as "Vista capable," meaning that they will have enough memory to run the new operating system, in hopes that customers will buy now and upgrade their operating system rather than wait until Vista debuts to buy.

The data arrived ahead of next week's tech earnings blitz. Apple (Research), IBM (Research), Intel (Research) and eBay all report quarterly earnings next week. (HP (Research), like Dell (Research), does not report on calendar quarters; January sales were included in the company's earnings when it reported its most recent quarterly results in February.)

The trend of laptops out-growing desktops continued. Of the companies and retail stores that Current Analysis tracks, first quarter laptop sales grew 43.6 percent over the previous year, while first quarter desktop sales grew 16.3.

"Price point has a lot to do with it," said Bhavnani. "The average selling price of notebooks has fallen at a quicker rate" than that of desktops, he added, noting that from last year's first quarter to this year's first quarter, the average selling price of notebooks fell 20 percent, down to $984.

"The average notebook has fallen below the $1,000 barrier," which is a psychological block to consumers, Bhavnani said. That means buyers may be more willing to shell out for a lap top.

HP's Compaq line sold 354,000 computers, a 69 percent increase from the previous year. Compaq experienced a 79 percent growth in desktop PCs and a 55.3 percent growth in laptops. Competitor Gateway recorded explosive growth in its laptop PCs. Sales of Gateway laptops grew 166.3 percent from the first quarter last year to the first quarter this year, while desktop sales grew 36.8 percent.

Unlike PC makers, Apple is immune to any negative effects of the Vista delay. But it faces a problem its PC competitors do not: It's currently transitioning its entire line to Intel processors, which means it has to get rid of its non-Intel-based inventory.

Goldman Sachs analysts estimate that Apple shipped about a million Macs in the quarter, making for roughly flat year over year growth. That's in part because of the company's slow ramp of its MacBook Pro Intel-based laptop as well as some stalling in iBook sales in anticipation of the Intel-based line, which is expected as early as this month, the analysts wrote.

The Goldman Sachs analysts also think iPod sales will drop off sharply from last quarter's record 14 million units sold. The analysts estimate that apple shipped 9.25 million iPods this quarter and suffered from greater "seasonality," analyst-speak for the slowdown that takes place in sales following the quarter that includes the holidays.

Bhavnani of Current Analysis does not own shares of the companies mentioned. The Goldman Sachs analysts who cover Apple do not own shares of the company, but Goldman Sachs does banking business with the company.

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