The May launch of Intel's Santa Rosa laptop PC chips, an upgrade to its popular Centrino package, put a damper on April notebook sales.

The world's two largest contract notebook PC makers both reported a decline in April laptop shipments, after strong sales in the first three months of the year. The decline was due to users putting off purchases ahead of the launch of new notebook PCs armed with Santa Rosa, according to DRAMeXchange Technology.

These users have been waiting for an opportunity to upgrade their laptop PCs and their OS at the same time, so the arrival of Santa Rosa laptops could boost sales of the new Windows Vista OS, the market researcher said. The new set of chips, launched in early May, increases wireless internet and processing speeds in notebook PCs when compared to the previous Intel Centrino package.

At the launch, the fourth generation of the Centrino wireless chip package abandoned its Santa Rosa code name in favour of its marketing names, Centrino Duo and Centrino Pro. Both versions come with Intel dual-core microprocessors, but the Centrino Pro is specifically targeted at laptops for business users. It carries Intel vPro software, which helps corporate IT departments manage fleets of laptop PCs.

Intel expects over 230 new laptop and desktop PCs to be built around the Centrino Duo and Centrino Pro this year.

Laptop PC manufacturer Quanta Computer, the biggest contract notebook maker, said last week that it shipped 2.2 million notebook PCs in April. The figure is a notable slip from 2.4 million laptops in March, an all-time high for a single month at the company. Rival Compal Electronics shipped 1.70 million laptops in April, its lowest figure for a single month so far this year and down from 1.78 million laptops in March. The March figure was its second highest shipment figure ever.

Quanta and Compal, which make notebook PCs and other products for customers such as HP, Dell and Acer, also reported lower revenue for the month.

Users looking to pick up a new Centrino laptop in May will have some choices, but most companies indicated their products will be out this summer, without giving a more specific time. Asustek Computer, Dell, and Lenovo all introduced Centrino-based laptop models they said will be out by the end of May. Asustek upgraded six of its existing laptop PCs with Centrino Duo, while Dell is offering the Latitude D630 and Latitude D830, and Lenovo announced the ThinkPad T61 and the ThinkPad R61.