Worldwide PC shipments were up 14.6% in the first quarter to 69.5 million unit, better than the 13.2% IDC thought it would be, but the US was up only 3.5% year-over-year as the states struggles through whatever economic bug it’s caught.

IDC expects the belt-tightening to show up this quarter too.

The US is also losing some of its historic influence to the emerging markets. The American share of the worldwide market fell more than two points to 23%.

IDC put EMEA and Asia/Pacific more than two points above forecast; Indonesia stood out, it said. Japan showed 1%-2% growth.

As we’ve grown to expect, it was notebooks that did it, particularly consumer notebooks and declining prices.

IDC VP Bob O’Donnell says the trend is moving from one laptop per household to one laptop per person.

Microsoft’s release of the Vista Service Pack had little impact on sales, the researcher said.

HP’s shipment growth outpaced the market but was the lowest of the top five vendors at 17.4% worldwide; flat in the US. Appears HP may have an excess inventory problem, if you listen to Gartner.

Dell, pushed by its retail initiatives, had its best quarter in two years, up 21.6%. Acer was third, but suffered a 20% drop in the US. Lenovo was up 21% and Toshiba was up 20.6%.

Dell remains the US leader with roughly 31% of the market to HP’s nearly 25% with Apple in fourth place with 6%, up 25.1%.

Worldwide HP has 19.1% to Dell’s 15.7%, with Acer at 9.9%, Lenovo at 6.9% and Toshiba at 4.4%.