If it continues to cling to its vision of DRM and User Account Control, if it continues to behave as if it had a divine right to 90 percent market share, Microsoft will create a situation that makes inroads by other OSes inevitable.
With what I've read of Vista'a DRM scheme, which appears to have been spec'ed by the media conglomerates and RIAA, this issue alone may be the stumbling block to sales.
So what's the issue? If you don't like DRM, then don't play protected content on your PC. Pretty simple. If you are quite happy with standard definition DVDs, nothing has changed for you, except that Vista Ultimate includes a DVD codec. If you want HD content, then you're subject to whatever protection the publisher demands for their product.
I've read the Vista takes the initiative to DOWNGRADE reproduction of "suspect" sounds and images. To maintain predictable resolution, i've read, you need to avoid Vista. True?