Microsoft will discontinue extended support for Windows 98, Windows 98 Second Edition and Windows Millennium edition from 11 July.

The move, which is being made in accordance with the Microsoft Support Lifecycle Policy, effectively means that the software giant will end public and technical support, including security updates, by this date.

Microsoft said that existing support documents and content will continue to be available through the Microsoft Help and Support website.

"Microsoft is retiring support for these products because they are outdated and can expose customers to security risks," the company said.

"We recommend customers who are still running Windows 98 or Windows Me to upgrade to a newer, more secure Microsoft operating system, such as Windows XP, as soon as possible."

Microsoft will also end all public assisted support for Windows XP Service Pack 1 on 10 October. This means that the firm will no longer provide any incident support options or security updates for this retired service pack.

"To enhance the security of your computer and to continue to receive updates for Windows XP, we recommend you upgrade your computer, for free, to Windows XP Service Pack 2," Microsoft said.

However, the company stated that it will make Custom Support Agreements (CSAs) available for "eligible enterprise customers under qualified conditions" .

But CSA customers are also encouraged to consider switching to Windows Vista as part of their migration plans.