Microsoft has confirmed that there will be no equivalents of its Windows XP Service Pack 2 to boost security on earlier operating systems.

The announcement leaves the 50 per cent of Microsoft customers not currently using XP with the choice of upgrading or relying on platforms that will become increasingly less secure.

While fault patching will continue in line with pre-existing support cycles, there will be no more operating system service packs other than for XP.

"You should not expect the equivalent of SP2 for Windows 2000; there are limits to the technology," Detlef Eckert, chief security advisor for Microsoft in Europe, told vnunet.com.

"You would have to effectively replicate XP on the 2000 code which makes no sense. We believe that technology designed before the internet had taken off will always have problems."

Standard support for Windows 2000 Personal and Server editions ends on 30 June, although companies can pay for an extended version. Support for Windows 98 and NT4 has officially ended, although some patches are still being released.

"The primary reason for this decision is driven by the need to get people to upgrade," said Graham Titterington, senior analyst at Ovum.

"Microsoft has been finding it increasingly difficult to get people to upgrade, as existing software has so many features that people don't see the need to upgrade.

"Also remember that Windows 2000 was supposed have been designed from the ground up to be secure, at least that's what they told us at the time."

Eckert also confirmed that there will be no more browser releases until the arrival of the new Longhorn operating system.

He indicated that the changes to Internet Explorer made in SP2, such as blocking popups, essentially made it a new browser anyway.

Longhorn is not due till 2006, although analyst firm Gartner predicts that the full operating system will not be available until 2007. The software was originally due in 2004.