The search in Windows Vista is fundamentally flawed and simply cannot find
many files regardless of your settings. My guess is I cannot find 20-25% of
the old files on my machine because Windows simply won't search them. If
you have any files with a "wrong" extension Vista just ignores them. I have
wasted hours in 2007 with manual file-by-file searches since Vista's search
cannot find files I know exist.

The Windows Vista Advance search techniques page was intended to explain how
to use the new search, but it is now documentation about the failures of
search in Vista:
Windows Vista Team Blog : Advanced search techniques

So far only silence from Microsoft about any fix or workaround, and just
another reason to go back to Windows XP. Search in Windows 2000 was better.