MS sell more of windows because it's cheaper, not because it's better.
There are tons of reasons why Microsoft sells more software than anybody else, and the price has almost nothing to do with it. Here are just a few reasons in no specific order:
- The sell a platform, not just loosely coupled pieces of software.
- That platform can be customized(!) and extended(!) by anybody who wants to do so. (For example, Microsoft's embedded platform comes to OEMs in a similar "Lego bricks collection" as Linux - OEMs are in complete control over the system and how they want to use it. But even the desktop Windows version can be customized to the customer's requirements.)
- Microsoft understands the OEM business better than anybody else.
- Microsoft uses a "divide and rule" policy: As long as people pay license fees, they let anybody play in their market. (Where Apple is only interested in Apple and avoids competition wherever possible.)
- Microsoft actually listens to its customers (which would mainly be Enterprises and OEMs) and designs the products to their requests.
- Microsoft ships products that Enterprises ask for. (Just look at Sharepoint Portal Server, if you want an outstanding example for this.)
- Microsoft ships products that gamers and game developers ask for.
- Microsoft ships products that software developers ask for. (There are reasons why Visual Studio and .NET are the killer development environment that they are and why developers swear by them.)
Apple competes with Microsoft only in the consumer market; which is just ONE business segment of Microsoft Corporation. In the Enterprise market, Apple is a complete no-show - Apple doesn't have any software products for this market, and even their hardware portfolio only covers a few bits and pieces that you'd need in the Enterprise field. Dell and several others have the required products, but Apple doesn't.