Well Microsoft is planning a second half of 2006 release, that's been officially announced. While there can be delays, and it wouldn't be a surprise your 2007 comments are pretty vague and out of date ')
Regardless widespread implementation may take well into 2007/08 and hardware complications can always be dealt with then.. I just wanted to provide the link
and this one.. "arriving 2006"
http://www.microsoft.com/windowsvista/default.mspx