Open vs. closed is perhaps misleading, but at the very least it's obvious that MS targeted high-volume sales with Windows while Apple targeted low-volume sales with the Mac / Mac OS. Apple built in a huge profit margin on its end-to-end system, putting it out of reach of much of the market. MS built in a smaller per-unit profit on its OS, but since the incremental cost of software is negligible this put them in a much better position since increased volume increases their profit margin almost without limit.