It would be handy to have a task to perform the Which/Where path search.
Part of my build pattern is determining if all prerequisites are installed, and determining their inclusion in PATH by doing a Which/Where search.
Something like the following is what I'm looking for:
<which file="robocopy.exe" property="prereq.robocopy" failOnError="True"/>
The full path of the executable would be stored in the property value.