Don't think there is one... it's best off asking the manufacturer whether
they'll support your hardware.

Are you referring to the componentized version of Windows? I am not sure
there are any available yet, Windows Embedded Editions of Microsoft
operating systems are usually released 90 days after the release of the
initial product. As Zack mentioned get in contact with current XP Embedded
OEMs to find out about their Vista strategy, when you can likely expect to
see Vista Embedded products and solutions on market after Vista's launch.

Its also possible that the current XP Embedded toolset should be compatible
with Windows Vista, which means you can use existing devices designed for
XPe with Vista.
Check out the blog:
http://blogs.msdn.com/embedded/

E-mail: http://blogs.msdn.com/embedded/contact.aspx

Please note, this information is possibly obselete;
Longhorn Embedded:
http://blogs.msdn.com/mikehall/archive/2004/08/29/222498.aspx