Symantec spokesman Chris Paden sees Microsoft "leveraging a monopolistic position to limit customer choice" as the company works to include better security features in Windows Vista. Robert McMillan wrote for Macworld UK: "Microsoft says it is adding these features to lock down the operating system, but Symantec believes that they will be harmful to customers by making it harder for them to use third-party software."

However, Mr. Paden didnit want to accuse Microsoft of engaging in anti-trust violations, a delicate topic given the legal proceedings against the company in the U.S. and Europe. He noted: "Itis not anti-competitive behavior, because Vista hasnit even hit the market yet,."

As it did during the browser wars by tying Internet Explorer so closely to its operating system, Microsoft is being so close to the vest with security that it is keeping developers from accessing the Windows kernel. Eric Sites, vice-president of R&D at Sunbelt Software, said: "There are a lot of new exploits coming out that exploit kernel-level drivers, " he said. "If weire able to get into the kernel, we can watch for things like that, but with what Microsoft is doing we canit do that."

Microsoft declined requests for comment, but Mr. McMillan cited a quote from Stephen Toulouse, the companyis senior product manager in the security technology division, given to IDG News last week: "What weire doing is weire walling off the kernel from attackers, because the functionality that is currently there was never meant to be used by anybody -- by software vendors or attackers."