In Singapore today, he hit out at the Redmond, Wash., company's .Net software tools before the region's assembled press.
"The world is down to two developer camps:, the other is Sun ONE Java. Java is the No. 1 development platform. Viruses are a feature in .Net, but Java has security built in. I find it funny how the default setting in Win XP lets in Office macros but blocks Java," he told an amused audience.
"Sun ONE runs on every system and processor," the CEO said. ".Net runs only on Windows. It?s mankind versus Microsoft. .Net is a joke."
Microsoft was not immediately available for comment.
In Beijing on Monday, McNealy poured scorn on the software giant's scheme tooperating system to governments, a move designed to reassure officials that there was no sinister back door in the software.
He described it as bait--"cheese"--that lulled officialdom into a sense of security. The Sun CEO expressed doubts that Microsoft would reveal all, saying that the software company would try to keep key components secret.
But a note of humility seemingly crept in when he was asked if Sun could eventually triumph. McNealy said that his rival's deep cash reserves posed a formidable challenge.
"It's difficult for me to defeat Microsoft. Microsoft has a lot of cash in hand," he said.
CNETAsia's Winston Chai and ZDNET China's Ken Gao contributed to this report.