There is an article about this ad today in USA Today online.
It was a teaser ad, now the "real" ads come out, or as Microsoft says, chapter II. The ads were about nothing, like Seinfeld's show was about nothing. Now they are going to be more direct in promoting PCs and Windows, to counter Apple's ads of the past couple years dissing PC users as washed up geeks, while Apple users are more hip.
I'm not in advertising, but as a consumer I thought they were a waste of money. It's not like the Superbowl where they string a series of commercials together right then and there. Watching the Gates/Seinfeld commercials without a clue what they were getting at until reading about it today just seemed like a waste to me, but they were entertaining.