and how long before a PC dev has to pay MS for each sold copy (just like console games), and how long before MS makes DX not-free unless you participate in GFW.
Exactly. Even though the PC is an open platform in the sense that third-party development tools and libraries can be used, Microsoft can leverage its control over the OS to make using those third-party tools and libraries difficult if not impossible. Microsoft already does this with its DirectX SDK's by only supporting its own languages and compilers. By tying DirectX 10 to Vista Microsoft has ensured that developers and consumers must use Vista to get the benefits of DirectX 10 and by bundling the game browser and Live service into Vista and into its SDK's, Microsoft has made it the default method of incorporating that functionaily into games for Vista.
Sure developers could forgo paying Microsoft to have their games certified for Windows and appear in the game browser, but what commercial game developer is going to want its games to not show up there when its competitors' games do.