I do IT consulting for a living. I've been doing computers and the Internet since before most folks knew that either existed. I switched to Mac a little over 3 years ago and have no intention of switching back. There are lots of reasons why that aren't necessary for this conversation. That being said I have to remain competent on many platforms.
From a photographic standpoint, it really doesn't matter much. Roughly the same tools are available on both platform. Where Apple wins, IMO, is color management. It's end to end. Windows is still playing catch-up there.