The impending update to the Windows XP operating system is expected to give end users more control over applications that launch by default on their PCs, as well as more advanced wireless connectivity.

Microsoft is set to deliver Windows XP Service Pack 1, a set of bug fixes, feature upgrades and technical tweaks, to manufacturers sometime "in the next 10 days," said Charmaine Gravning, product manager with Microsoft's Windows division. Soon after it is delivered to manufacturers, users will be able to download it or purchase it for a nominal cost on a CD.

Microsoft is required to make it available to all users by 6 November in order to comply with its proposed antitrust settlement with the US Department of Justice.

Service packs are standard to Microsoft's operating system release cycle. However, the package of updates for Windows XP is especially notable because it will introduce changes to the operating system that bring Microsoft up to speed with the proposed antitrust settlement. For one, users are expected to be able to manually set the default 'middleware' applications that open when machines running Windows XP boot up.

Microsoft has built into the Start menu two new tools that help it comply with the proposed settlement deal. One is a function that allows users to add and remove their Microsoft middleware applications. A second addition is a menu designed to allow users to "set program access and defaults", to determine which middleware applications open automatically. For example, instead of launching Internet Explorer to view a web page, a user could set the default to launch the Netscape browser, or they could choose to launch RealPlayer instead of the Windows Media Player to play back audio or video files.

But in its early incarnation, the menu will give users only a limited choice of applications from developers other than Microsoft. To make their applications appear in the new menu, third-party vendors must tune them with a set of APIs (application programming interfaces) Microsoft has disclosed under additional requirements in the proposed consent decree.

So far, no third-party vendors have made use of those APIs, Gravning said. Users who have already set a third-party application as a default by some other means will have the choice to continue using their current settings.

The noticeable changes will occur on PCs configured by OEMs (original equipment manufacturers), according to Rob Enderle, research fellow with Giga Information Group.

"This is more targeted at the OEM installation so when they ship a PC they will provide a load of software to choose from," Enderle said. OEMs are expected to work with vendors to outfit their applications to appear in the default setting menu, he said.

Other minor upgrades to the operating system include some changes to the controversial Product Activation feature, created to prevent a single copy of Windows from being illegally installed on multiple machines. This requires a user to have a unique product key to run the software.

Users who attempt to install a single copy of Windows XP on a second PC will be prevented from doing so, and will now be pointed to a Microsoft website that allows them to purchase a second product key online. Microsoft will begin discounting the price of these additional product keys so that they are around $20-$30 (up to approximately £19) less than the full cost of the operating system, Gravning said.

With the service pack, Microsoft will also outfit its latest operating system to work with its new technology, codenamed Freestyle, which allows users to manage their PCs with a remote control.

Windows XP Service Pack 1 will also add support for new computers such as the Tablet PC and the Mira desktop computer, officially known as the Windows Powered Smart Display, whose monitor and CPU are connected wirelessly, allowing users to access their hard drives and the internet from the detached monitor.

These technical changes won't be apparent to current Windows XP users because Mira and Freestyle will only work on specialised PCs in development by some OEMs. HP is planning the release of an entertainment-laden PC, based on Freestyle and featuring TV and VCR functions, which is officially known as the Windows XP Media Center Edition.