further information:
"What's changing is Microsoft is giving six more months where it will
provide downgrade media for XP Professional for OEMs and system builders to
provide to their customers who purchase Windows Vista Ultimate and Business
editions - (which the company figures will be) largely going to be small
businesses since that's the audience that would want/use XP Pro. So it's the
same old downgrade right thing that was in the EULA (End User License
Agreement) before; it's just Microsoft is providing the media to partners a
few months more."
"The same caveat with providing the downgrade media as before applies,
which is OEMs and system builders don't have to do so if they don't want -
it's their business decision to make."
http://blogs.zdnet.com/microsoft/?p=1619
so you can see its not up to microsoft... it's the OEM or system builders
responsibility to provide you with this option
and if they don't care, they are not forced to do this!