Microsoft might re-think its plan to phase out the Windows XP operating system by 30 June.
The company has also said XP will remain an option in developing markets for cheap PCs until 2010.
"XP will hit an end-of-life. We have announced one. If customer feedback varies we can always wake up smarter, but right now we have a plan for end-of-life for new XP shipments," Ballmer said.
Microsoft plans to end licensing XP on computer manufacturers' machines by 30 June. Microsoft also plans to end retail sales on the same date.
But Ballmer however, "In the business environment, we still have customers who are buying PCs with XP because information technology departments often have to work with old machines."
Microsoft is currently distributing Service Pack 1 of its year-old Windows Vista OS.