Recently announced, applications that will run on RT has to be 'certified' by Microsoft to be added to the list of programs on their store. This means that similar to other platforms such as Apple's Mac, not all programs will effectively run on Windows RT if it hasn't been checked by MS to adhere to certain standards.
Now, although this is good in practice, the one thing that made the PC as a computer original was its compatibility and changeability. With a PC computer you always have the choice of using computers like you want, customizing it completely. Sure, there were multiple compatibility problems with various systems, and there's no dodging away from that. But although not as open-formed as Linux, Windows gave you options by not limiting your choices.
Windows 8 won't have this system yet, so its still free game, but the direction that Microsoft is moving might be a troubling one for those who enjoyed the freedom that a PC offered with Windows' open system. I personally also enjoyed the large choice I had with Windows and PC's so far, leaving me slowly losing even more faith in Microsoft's new business model.
