Microsoft has issued a reprieve to Windows 98, 98SE and Millennium Edition users by extending support until 30 June 2006. Support was due to end on 16 January.
The company said that the move was in response to client needs and to bring Windows 98SE's lifespan in line with other products.
"Never say never but we're unlikely to extend this again," said Lars Ahlgren, global services marketing manager at Microsoft.
"We want to do the right thing by our customers and, while the extension may have looked like an easy decision, we've devoted considerable investment to this extension.
"But some people will never change from Windows 95 or 98: it does exactly what they want."
But others suggested that the U-turn indicated Redmond's fears that users would turn to open source alternatives rather than upgrade.
Last week both SuSE and Red Hat said that they would be targeting Windows 98 customers in light of the end of support.
Even after Microsoft's change of heart, some resellers are already moving in.
Clarity Technology is discounting prices for companies which migrate to open source. Until June customers will pay £30 per user.
"Instead of taking this lying down, companies of all sizes should take this opportunity to look at alternative open source solutions," said Chris Whitely, UK enterprise solutions manager at Clarity.
"There might be extra functionality in the new Microsoft software, but do customers really need it?
"They certainly haven't asked for it. And they definitely haven't asked for the extra cost of the hardware upgrade which will be needed."
Support for Windows NT 4 is due to finish at the end of the year and for NT Workstation 4 by the end of June. Microsoft has not commented on any plans to extend the support period for these products.
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