Report: Vista more vulnerable than Windows 2000

On the other hand, Vista is 37 percent more secure than Windows XP, according to the report from the vendor, PC Tools.

Statistics gathered from users of PC Tools' ThreatFire security service indicate that Vista allowed 639 threats per thousand computers. That compares with 586 for Windows 2000, 478 for Windows 2003 and 1,021 for Windows XP, according to company statistics.

With an infection rate of 639 per 1,000 PCs, that means 64 percent of Vista users could expect their PCs to be compromised by malware.

The ThreatFire anti-malware service attempts to stop malicious software based on its behavior rather than by the signature-matching technique used by most anti-virus products.

"Ironically, the new operating system has been hailed by Microsoft as the most secure version of Windows to date," Simon Clausen, CEO of PC Tools, said in a prepared statement.

"However, recent research conducted with statistics from over 1.4 million computers within the ThreatFire community has shown that Windows Vista is more susceptible to malware than the eight-year-old Windows 2000 operating system and only 37 percent more secure than Windows XP."

Neither PC Tools nor Microsoft responded to SCMagazineUS.com's request for comment.