With a 30.9 per cent increase in sales, Apple grabbed 5.7 per cent of the US computer market in the fourth quarter of 2007, IDC claims.

These figures are echoed by those from Gartner, which peg Mac sales as up 28 per cent in the quarter. Both research firms place Apple as now the number four computer manufacturer in the US.

IDC notes that Apple's climbing sales continue to eclipse the industry average, which hit a 15.5 per cent climb in the quarter on a global basis, the figures show. Gartner claims total worldwide PC shipments rose to 271.2 million.

Of the PC manufacturers, Acer saw shipments climb 60.3 per cent. HP returned a more modest 17.1 per cent growth, while Dell saw sales climb 15.2 per cent, IDC said.

However, IDC warns that economic gloom is likely to slow industry growth in the next couple of years.