Excerpt - Microsoft Corp., weary of being cast as a stodgy oldster by Apple Inc.'s advertising, is turning for help to Jerry Seinfeld. The software giant's new $300 million advertising campaign, devised by a newly hired ad agency, has been closely guarded. But Mr. Seinfeld will be one of the key celebrity pitchmen, say people close to the situation. He will appear with Microsoft Chairman Bill Gates in ads and receive about $10 million for the work, they say. ~ snip ~