Vista does detect the file. You can also use "DIR /R" command in vista to show Alternate Data Streams (it's not supported in XP).
Did you create the file before opening in notepad ?? I mean did you do something like "ECHO Hidden Text>Test.txt:Hidden" before "notepad Test.txt:Hidden" ?? If not, then no ADS is present with Test.txt, so notepad won't find any ADS.
New-link : http://sourceforge.net/projects/unxutils
. (Will update the article)