For ages now, I've forloned my ability to find a suitable analog for the unix "which" command, under Windows. Understandably, any Google search containing the words "which", "windows", returns a series of results that are as good as useless. It was consequently quicker to write my own. It currently lives at which.pl. I've saved it with the .txt extension to permit easy downloading, less Windows try to execute the script when you click on it.
For those wanting a more involved description, I suggest you use the source Luke! It's a trivial 30 line piece of Perl, which could no doubt be optimised. It simply splits the path into component directories and checks for the existence of the command by appending each executable extension (.exe, .bat, etc) to the stub name.