A row has broken out between rival anti-virus companies about their readiness to provide protection for Microsoft's new operating system.

McAfee and Symantec have both complained that without access to the 64-bit code for Windows Vista they won't be able to develop products for it.

Sophos waded into the row on Monday when it claimed that both McAfee and Symantec should have prepared better for the launch of Vista.

"Symantec and McAfee may be struggling with host intrusion prevention (HIPS) because they haven't coded their solutions with high-spec Vista in mind," said Richard Jacobs, chief technology officer at Sophos.

"Additionally, Sophos is building its technology by making use of supported Microsoft interfaces rather than by trying to subvert them. That's why we're ready for 64-bit Vista, and others aren't."

McAfee has hit back at those claims and has dubbed Sophos a single-product vendor that doesn't face the same challenges.

"It is crucial that readers understand the difference between McAfee and those companies that focus on anti-virus software alone," said Siobhan MacDermott, VP of worldwide corporate communications at McAfee.

"Single-product vendors, like Sophos, may well not have an issue with Microsoft."

McAfee pointed to comments made by Gartner security analyst Neil MacDonald, who backed up McAfee's claims that Sophos is not affected in the same way as its rivals.

MacDonald said that Sophos "didn't have the same capabilities" and wouldn't be affected in the same way as the other companies.

McAfee warned Microsoft that its "flawed logic" would only result in making computers more vulnerable to viruses and other attacks.

"To protect customers from the bad guys, you don't lock out the good guys," said MacDermott. "Internet security is everyone's business, and we hope that Microsoft will return to the collaborative approach that has served customers well in the past."

The problem is caused by Microsoft's Patchguard prevention system, which Symantec and McAfee claim has locked them out of the Vista operating system kernel and is anti-competitive.