It will be interesting to see if Jerry Seinfeld will help Microsoft’s new $300 million “Windows, Not Walls” ad campaign when it launches Sept. 4. Seinfeld is expected to snag $10 million to be Microsoft’s new celebrity pitchman.

Microsoft is indeed having major problems. In this week’s latest report of the American Customer Satisfaction Index (ACSI), a highly respected tool developed 15 years ago by University of Michigan Professor Claes Fornell, Apple is leaving “all rivals in the dust” when it comes to personal computers. Compared to Apple’s index score of 85, customer satisfaction with PC is continuing its retreat, most recently posting an index score of 74. The money quote from Fornell:

“Except for Dell (up 1%), the drop is connected with the Windows-based machines - Hewlett-Packard, Gateway, and Compaq are all down by 4%. Not only is Apple bucking the slide, it registers its greatest ACSI increase ever (up 8% to 85) to lead the industry by a wide margin. The satisfaction of Apple PC customers is 13% higher than Dell in second place and 21% higher than Compaq. This is one of the largest gaps in customer satisfaction in any industry covered by ACSI. It is also a record high for Apple.”

Fornell suggests that Apple has finally mastered the synergy of its iPhone and iPod business with its computer product lines. Sales of Apple products are up almost 25 percent and net income is up nearly 75 percent from a year ago.

As for the continuing softened base for Windows-based platforms, Fornell targets the new Vista operating system as the culprit:

“Customers have complained about usability of the new system, sluggish processing speeds and problems of software compatibility, while hardware requirements have led to complaints about price. Another problem has been that many owners of older machines have felt compelled to purchase the Vista upgrade in order to stay current. Even though Vista is just one (albeit very prominent) piece of software in the Microsoft catalog, the ACSI score for Microsoft (released in quarter 1) is showing a development similar to the Windows-based PCs makers.”

Perhaps Steve Jobs should call Michael Phelps.