The software giant said it was prompted to make a u-turn after it emerged that some developing countries where Windows 98 is still widely used, including Kazakhstan, Ivory Coast and Slovenia, were not aware of the deadline.
Microsoft's rethink means that users of Windows 98 and Windows 98 SE will now be supported until June 30 2006, until which time the company will offer paid phone support and review security threats to determine whether it will provide customers with security patches.
About 20% of all Windows-based computers still run Windows 95 or 98, according to International Data Corporation, a technology market research firm. Support for Windows 95 ended on December 31 2001.
A Microsoft spokesman, Matt Pilla, said: "While we've done an excellent job communicating our life cycle policy for most of our products, we have found that we could use more time to communicate those guidelines in a handful of smaller markets."
Microsoft's move is also likely to be a reaction to the threat of losing customers who switch to the freely available Linux operating system.
The technology news website ZDNet UK quotes Lars Ahlgren, a senior marketing manager at Microsoft, as saying that Microsoft is hoping that by extending support for its older operating systems, customers will stick with the company's products in future.
"The more they are used to working one way, the more [it is] likely they will want to continue working that way, so it plays to our advantage," Mr Ahlgren is quoted as saying.
In October 2002 Microsoft extended the period of support for new products from four years to seven years.
Good news for Fozzer
Does Herefordshire count as a third world country? 
