Microsoft will next week discontinue a feature that allows organisations to block the downloading of its Service Pack 2 (SP2) security update for Windows XP.

The company released SP2 last September to bolster Windows XP security features, and encouraged consumers and businesses to download the patch to minimise exposure to a growing range of digital threats.

The automatic downloading of SP2 could catch a large number of IT directors unawares. A survey published last week by supplier AssetMetrix shows that just 24 per cent of users of US corporate PCs running XP have voluntarily installed SP2.

Until now, organisations have been able to receive other security patches and updates from Microsoft while blocking the installation of SP2 until they have completed compatibility testing with their internal applications. Gary Barnett, research director at analyst Ovum, applauds Microsoft's decision.

'It's about time users had this update,' he said. 'You can't go on whining about security without installing key patches that Microsoft has made available.'

Organisations that still want to delay installing the update can disable Windows' automatic update facility, although this means they will miss out on any other updates released.