Shipments of Microsoft's Windows NT operating system for server computers will top Novell's NetWare in Asia-Pacific for the first time this year, according to International Data Corp (IDC). Sales of server operating systems in Asia-Pacific, excluding Japan, are expected to drop 13 per cent from last year to US$3.4 billion. This is despite an estimated 15 per cent growth in unit shipments to 270,000 from 235,000, IDC said. The economic slump and political unrest in the region, as well as falling prices, hurt sales, especially in the high-end segment, including Unix and OS/390, IDC research manager Avneesh Saxena said. Unix's performance was still better than expected, he said. 'Unix should have declined much more than it actually did.' Unix sales will drop 18 per cent to $1.5 billion by the end of the year, although unit shipments only fell 7 per cent. Although it lost the most ground, compared with Windows NT and NetWare, Unix remains popular with new high-end machines of more than $1 million from Hewlett-Packard, Sun Microsystems and IBM, Mr Saxena said. Unix also increasingly was being used on PC servers driven by Linux. Unix is expected to achieve annual growth of 7 per cent in unit shipments over the next five years. Windows NT was the only server operating system for which sales remained robust during the year. 'It has been growing at its own pace, unaffected by anything,' Mr Saxena said. Year-end revenues for Windows NT will rise 10 per cent over last year, with units shipped up 30 per cent. NT is gaining ground on NetWare and it is unclear whether it has surpassed its rival in the number of actual users. But the spread of Windows NT could be slowed by increasing competition from Linux, which is cheap or free to install, and based on an 'open source code' model whereby a community of developers and users provide each other with technical support and new innovations. Though the number of machines running Linux remains small, it is growing quickly and is regarded as a credible alternative to NT. Novell NetWare shipments are expected to be up 13 per cent this year, though revenue will be down 6 per cent. The launch of NetWare 5 in September had not brought about significant growth, Mr Saxena said. 'But [it] helped [Novell] retain its installed base by showing its ability and willingness to innovate.' The major change in NetWare 5 over previous versions is its complete migration to Internet protocol. Novell's sales were down 39 per cent in Asia-Pacific in the most recent quarter, despite an 11 per cent increase worldwide.