Second this podcast. Ballmer basically setup Microsoft as the enterprise software company. From the first episode it seemed that Bill was actually more interested in the consumer side of things and wasn't that interested in the enterprise, but it was Ballmer that basically setup that entire business line in the first place especially with him managing the OS/2 with IBM and later NT.

I think a lot of fails for MS during the Ballmer era was them toeing the line post their anti-trust.