Bill Gates and Microsoft were reasonably visible since... a long time. I think it's not easy to make that kind of money and stay out of the spotlight. And since Microsoft was always fairly consumer oriented, they needed the publicity, too.
In the beginning, Microsoft was not all that visible outside the hobby market. In the early days, Intel had a negative opinion of them, and was pretty skeptical about their C compiler, for example.
It seems to be fair to say that they were not that visible for quite a period.
And for a long time, they, particularly Bill Gates, was severely underestimated. That was the parlor game of the day for journalists--underestimating Bill Gates.
http://www.snopes.com/photos/people/gates.asp