I look at it this way: the entire industry was utterly cutthroat (still is, in many ways). If Bill Gates/MS didn't do what they did, I believe another company would have. That doesn't mean they are utterly innocent, but in terms of effect on my life, I'm not convinced an MS-less life would be that different.

On the other hand, if Bill Gates doesn't spend money curing diseases in the third world I'm not at all convinced that someone else would come along and fill in that space. After all, they could very easily match him today with all the work there is to do.