Overall, consumers rated their satisfaction with the maker of their PC 3 percent worse than last year, according to the American Customer Satisfaction Index (ACSI), the annual quality study conducted by the University of Michigan set for release Tuesday.

Apple is still the leader in terms of satisfaction with service and products, but its overall ranking dropped by five percentage points this year. Dell also lost five points on its score. Hewlett-Packard's HP brand showed a 1 percent improvement in a year, while its Compaq label is still rated the worst.

This survey is indicative of consumer satisfaction in general, which increased a mere 1 percent since the second quarter of 2006. Though American consumers' satisfaction has increased for the last nine quarters, that rate of satisfaction is slowing, said Claes Fornell, director of the National Quality Research Center at the University of Michigan, which conducted the study.

"It probably means for the economy at large that we will see a slowdown in consumer spending (next quarter) and consumer demand as well," he said. "We've seen a pretty strong correlation between customers and how satisfied they are and their future purchase behavior."

Admittedly, customer satisfaction is a hard thing to measure, he said. Fornell's group conducts the survey by asking 80,000 customers of the leading PC makers a series of questions related to how they view service quality, price, problems, future or repeat purchase plans, and satisfaction related to expectations.

Among PC vendors, Apple still leads the pack with a score of 79, and Compaq comes in at 73. On a scale of 100, any score in the 70s is respectable, and any rating above 74 means you're doing "quite well," Fornell said.

Apple's drop, even if it is ever so slight, is unusual since the company is usually ranked well on most aspects of the ACSI survey, Fornell said. He points to the Apple's growth as a possible cause, as well as the enormous expectations that come with being a quality leader.

"It's almost like what goes up must come down," he said. "They have done so well that they have increased their business by 400 percent in the last five years. That puts a certain strain on resources. With many more customers to service, it's not that service quality is going down, as much as the reliability of the products." Survey results refer only to Apple's computer products.

Apple spokeswoman Natalie Kerris said, "Customer satisfaction is very important to Apple. While we're pleased that we're still No. 1, we're going to try even harder."

Dell also dropped 5 percent after raising its ranking last year. Dell's problem is customers' perception of product reliability as well as service, Fornell said. As examples, just this year, both shipping delays of the much-anticipated XPS M1330 notebook and the New York Attorney General Office's decision to sue Dell for consumer fraud have made news.