Search results posted by Google, AOL, and Ask.com are less likely to lead to dangerous sites than they did six months ago, a report published Monday said. MSN's and Yahoo's results, however, send users to more risky sites than in May.

McAfee SiteAdvisor, a safe browsing service, collated the new numbers as a follow-up to a May 2006 survey of several thousand keyword searches that found 5% of the links served up by Google, Yahoo, MSN, AOL, and Ask.com send people to sites that can infect computers with malware or plague users with spam.

Last month, the same searches linked to 12% fewer sites judged risky by SiteAdvisor; overall, 4.4% of the sites returned by the five search engines were tagged with red or yellow warnings by SiteAdvisor in November.

"It's good to see that clicking on search engine results has gotten modestly safer," said Chris Dixon, SiteAdvisor's director of strategy, in a statement. "But when almost one of 12 sponsored links still clicks through to a risky site, there remains significant room for continued improvement."

Ask.com showed the most improvement of the five search sites, but AOL took safest honors: just 3.6% of its results were pegged as potentially dangerous by SiteAdvisor. MSN, which held the safest spot in May, fell to fourth in November's tally. The SiteAdvisor report theorized that the safety decline was due to the expansion of MSN's paid search program.

Paid search results, in fact, remained about three times more dangerous than nonsponsored links: 8% of paid links were labeled risky by SiteAdvisor, compared to 3% of unpaid links. The results were similar to May's, when 8.5% of paid and 3.1% of "organic" links were tagged dangerous.

Other facts gleaned from the new SiteAdvisor report include twice the likelihood of a dangerous site in adult keyword searches than in nonadult, and a tripling in risk when searching for anything with the word "free." In Google's results, for example, 13.8% of all links obtained with a search containing the word were risky, compared with only 4.2% of all searches.

The November report can be found on the SiteAdvisor site.

McAfee SiteAdvisor recently expanded to offer a $19.99 Plus edition that includes a real-time link checker which sniffs out risky URLs embedded in e-mail and instant messages. A free version of the tool is still available for both Internet Explorer and Firefox.