I've never actually known anyone to be a Steve Ballmer fan. He's got business savvy, but as a presenter / public speaker he is a buffoon.
If 1/10 sales are Mac, then Apple is very happy. They are fine as a niche market, since they are obviously making money. They just beat their earnings estimate the other day and their stock is at its highest level ever. I've easily doubled my investment in Apple shares since I bought them when they were in the mid $90s.
MS needs Apple to force them to innovate and bring out better products. And the reverse is also true. Competition is good for all of us, Mac fans, Windows fans, and it's the best for folks like me, those of us who enjoy products from both companies.