Well it was inevitable and to be honest if you're still running either OS then you really should upgrade.
July 11, 2006 will bring a close to Extended Support for Windows 98, Windows 98 Second Edition, and Windows Me as part of the Microsoft Lifecycle Policy. Microsoft will retire public and technical support, including security updates, by this date.
Existing support documents and content, however, will continue to be available through the Microsoft Support Product Solution Center Web site. This Web site will continue to host a wealth of previous How-to, Troubleshooting, and Configuration content for anyone who may need self-service.
Microsoft is retiring support for these products because they are outdated and can expose customers to security risks. We recommend that customers who are still running Windows 98 or Windows Me upgrade to a newer, more secure Microsoft operating system, such as Windows XP, as soon as possible.
Customers who upgrade to Windows XP report improved security, richer functionality, and increased productivity.
The more surprising news is that support for XP SP1 will cease in October of this year, granted it's not a big job to upgrade to SP2 and in fact recommended the stability and insurance.
On October 10, 2006, Microsoft will end all public assisted support for Windows XP Service Pack1 (SP1). After this date, Microsoft will no longer provide any incident support options or security updates for this retired service pack under the policies defined by the Microsoft Support Lifecycle policy.
source