According to the Wall Street Journal, Seinfeld will be one of the key celebrities in the campaign, appearing in ads alongside Microsoft founder and chairman Bill Gates -- himself something of a celebrity.
The aim of the campaign is to dispel Microsoft's image as a boring brand as well as to reassure consumers who are worried by reports that Windows Vista is a less-than-reliable operating system.
At the same time as hiring some cool celebrities to work on the campaign, Microsoft has also hired what is arguably the coolest ad agency on the planet -- Miami's Crispin Porter + Bogusky.
The WSJ reports that Microsoft won't rely entirely on celebrity endorsement for the campaign, and it is likely to include video of a group of students who said that they did not like Vista trying out a version of Windows called Mojave. At the end, they are told that the software was actually Vista.
The campaign is set to break on September 4, and comes as Apple's share of the personal computer market is on the rise.
Apple has a long history of using celebrities in its advertising, with the likes of Bob Dylan, who has promoted iTunes, and Jeff Goldblum, who appeared in a number of ads promoting Apple computers.
More recently, it has taken a direct swipe at Microsoft with a series of ads featuring a cool character, who represents Apple, and a nerdy character, who is called PC. The ads were remade for the British market featuring comedy duo David Mitchell and Robert Webb.
One favourite internet viral clip features an ad Goldblum made for Apple in the late 1990s, with the sound slowed down so that it appears he is delivering his endorsement under the influence of large amounts of alcohol.
Seinfeld does relatively few brand endorsements, although has appeared in a campaign promoting American Express card, in which he starred alongside Superman.
He also made a brief appearance in a one-off ad for Apple that was shown during the final episode of his sitcom 'Seinfeld'. The ad was from Apple's 'Think Different' campaign, which showed footage of people who've made notable contributions to history, such as Gandhi and Churchill. The ad was edited to include footage of Seinfeld at the end.