Call it Microsoft's Wndows 7 "halo" effect.
Most PC makers gained ground in the latest edition of a major customer satisfaction survey because they like Windows 7 a lot more than they did its predecessor, the much-maligned Vista.
"Computer manufacturers have to live with the vicissitudes of the software that Microsoft makes," said David VanAmburg, managing director of the American Customer Satisfaction Index (ACSI), a survey founded by the University of Michigan.
"But they're benefiting now that customers are perceiving the quality of the machine to be better because the machines are easier to use," said VanAmburg, who credited Windows 7 for boosting scores.
Windows 7 launched last October to rave reviews by most technology analysts and pundits, and has been a huge hit for Microsoft, which said it had sold 175 million licenses for the new operating system through late July.
Dell's customer satisfaction score climbed two points, to 77 out of a possible 100, a 3% increase over the last year. Hewlett-Packard and Acer both posted gains of 4% to also rack up scores of 77, as did an "All others" catch-all category that includes systems sold by the likes of Asus, Sony and Toshiba.
"Almost every PC brand was up," said VanAmburg. "Only Compaq didn't move."
Although HP bought Compaq in 2002, it retained the brand name on some of its machines. ACSI, whose data on PC customer satisfaction goes back to 1995, continues to separate the Compaq nameplate from HP's when it queries consumers.
Dell's score was the highest for the Round Rock, Tex.-based computer maker since 2006, while HP's was its best ever.
"The overall effect of Windows 7 has been positive, just as the overall effect of Vista was negative in 2007," VanAmburg said.
In the last several annual surveys, ACSI concluded that Vista -- which quickly gained a reputation as slow and buggy -- had a lot to do with dropping satisfaction scores. Dell's score of 78 in 2006, for instance, plunged by four points in 2007, the year Vista debuted. On the flip side, smaller gains by "All others" in 2009 was due in part to the brisk sales of netbooks, which OEMs equipped with the older-but-better-liked Windows XP.