I agree with Dimitri915.
Surely Steve is the innovator...and the artist.

All of you forget about DESIGN!
We are talking about PERSONAL computers, and their OS. My 10 years old Titanium-Powerbook-G4 (1GHz) is simply beautiful, and still working fine with OS-X Tiger. I hope Apple will never drop this tradition.
Up to XP MS Windows was just a frustrating crap. Even OS/2 was much better. Actually the NT core is from DEC. I had less problem with ten-thousands of various Unix machines (clusters, and greeds) of a global enterprise world-wide, than my so called Windows PCs.
Positive: Steve and Bill brought computers to the broad public. Steve showed us that a computer can belong to the final art category as well.
Negative: Bill sold us junk-food, and blocked innovation. Both of them sell us products overpriced.
Finally:
Windows 7 starts to behave as a real operating system - I start to like it - however I still prefer OS-X.