Rob Fahrni:

Open source has its place and if you want it to become the dominant force in the software world here's a tip, write better software. Write it for folks like my grandmother, not for me. That means paying attention to all the little things, just like Apple does. Remember guys, the user interface IS the application to the end user, they could care less about the cool algorithm you implemented under the hood. Seriously.

He's exactly right. A large part of the success of Windows is that every device you can think of works with it (and that lack is part of Vista's uptake problem). Apple combines that with great workflow and integration to give an even better experience. It's not that open source can't be good; there's plenty of good OSS stuff around. It's that getting tight integration (as with MS Office or Apple applications) is nearly impossible.