Microsoft announces no playback of commercial HD movies in 32-bit versions of Windows Vista:

http://www.apcstart.com/site/dwarne/2006/08/1139/microsoft-cuts-another-feature-full-hd-playback-in-32bit-vista

It's only protected content that won't be playable.

And that is just a MS solution. Any 3rd party can produce a product.

Leave it to MS.....