Microsoft touted Windows Vista's lower patch count this week, saying it required about 20 percent fewer fixes in 2007 than the four-year-old Windows XP Service Pack 2.

Jeff Jones, a security strategy director in the company's Trustworthy Computing group who regularly cites vulnerability statistics, said that Microsoft plugged 45 holes in Vista during 2007 compared to 56 in Windows XP Service Pack 2 (SP2), the version of the aging operating system that was supplanted by SP3 only last week.

Microsoft also patched fewer flaws marked "critical" and "important" -- the top two rankings in its four-level vulnerability scoring system -- in Vista (36 total) than in XP SP2 (50 total). By Microsoft's numbers, the company quashed 28% fewer critical or important bugs last year in Vista than in XP SP2.

Jones' analysis came in response to users' comments about a similar report he published in January that trumpeted Vista's security status on its first anniversary, he said. "In the wake of my Windows Vista One Year Vulnerability Report, which compared the 'first year of availability' of several products, I received many comments along the lines of "of course Windows Vista beats Windows XP as it shipped in 2001, but what about the current Windows XP SP2?"

In the January report, Jones had compared Vista with the original version of XP, and called out statistics that said Vista had posted about half as many vulnerabilities in its first full year of availability as Windows XP did in its opening 12 months.

At the time, some users griped that the comparison was unfair because 2004's XP SP2 was the edition most commonly deployed, and had substantially upgraded Windows XP's security provisions.

"XP was introduced a long time ago when security was not the requirement it is today," said a user identified as "Jim" in a comment to a January Computerworld story on Jones' Vista-XP match-up. "A much better comparison would be to compare Vista with XP TODAY."

Even as Jones touted Vista, he downplayed the significance of the vulnerability statistics. "This is not an analysis of 'the security' of these operating systems," he said, acknowledging that just one factor -- in this case the patch count -- "can't measure the absolute 'security' of an OS.

"[But] all other things being equal, is it easier to mediate risk on a system that has 10 vulnerabilities in a year or one that has 100 vulnerabilities in a year?" Jones asked rhetorically. "Which has a more negative impact on your security team and risk management process -- deploying 10 security updates per year or deploying 100 security updates per year?"

Jones' latest report can be downloaded from the Microsoft site (download PDF).