SearchFileOnPath - Searching a file on the system

<System.Runtime.InteropServices.DllImport("kernel32")> Shared Function _
    SearchPath(ByVal tartPath As String, ByVal fileName As String, _
    ByVal extension As String, ByVal bufferLength As Integer, _
    ByVal buffer As System.Text.StringBuilder, ByVal filePart As String) As _
    Integer
End Function

' Searches a file on the system
' Returns the complete file path+name, or "" if file not found
'
' If searchDirs is omitted, then the file is searched
' in the following directories, in this order
'   1. the directory from where the app loaded
'   2. the current directory
'   3. the \Windows\System32 directory (if under WinNT)
'   4. the \Windows\System directory
'   5. the \Windows directory
'   6. the directories listed in the PATH environment variable
'
' Example: Debug.WriteLine(SearchFileOnPath("TestApp.exe"))

Function SearchFileOnPath(ByVal fileName As String, Optional ByVal searchDirs _
    As String = "") As String
    Dim buffer As New System.Text.StringBuilder(260)
    SearchPath(searchDirs, fileName, Nothing, buffer.Capacity, buffer, Nothing)
    Return buffer.ToString()
End Function