Cringely On Gates' Free Software Connection
Bah! MS did not standardise computing with DOS. IBM standardised computing with their open PC architecture, and MS-DOS just happened to be the OS chosen for it. I refer you to this comment, from a similar debate, quoting Andrew S. Tanenbaum's book "Modern Operating Systems".
Of course, as Jack Sams pointed out to Robert Cringely, Billy G had a consulting role in some of the design areas, but as he also points out, the decision to have the architecture open was there from the start on IBM's part, with nothing to do with Gates.