Bill Gates contended that IBM remains Microsoft's biggest threat. Many others would say it's Google or Apple. Now, the New York Times quotes that “VMware is definitely a threat,” said Gary Chen, an analyst at IDC, a research firm. “After Google, it is the company Microsoft fears most.” The story by Steve Lohr quotes people including Maritz and Tod Nielsen -- one of a series of former Microsoft veterans now working for VMware -- and explains the threat it poses to the Redmond company. Virtualization technology from VMware and others let PCs and servers run more than one operating system. Microsoft offers its Hyper-V virtualization technology in conjunction with Windows Server, reports.