Не факт, что установлен Excel. Надо искать файл mso.dll
'---------------------------------------------------------------------------------------
Private Declare Function SearchTreeForFile Lib "ImageHlp.dll" (ByVal lpRoot As String, ByVal lpInPath As String, ByVal lpOutPath As String) As Long

Function LocateFile(ByVal strFilename As String, ByVal strRootPath As String) As String
Dim strBuffer As String
Dim lngResult As Long
Const MAX_PATH = 260
LocateFile = ""
strBuffer = String$(MAX_PATH, 0)
lngResult = SearchTreeForFile(strRootPath, strFilename, strBuffer)
If lngResult <> 0 Then
If InStr(strBuffer, vbNullChar) > 0 Then
LocateFile = Left$(strBuffer, InStr(strBuffer, vbNullChar) - 1)
End If
End If
End Function

Private Sub Command1_Click() '-----Содержимое этого Саба пихать на свое усмотрение
Dim sPath As String
sPath = LocateFile("mso.dll", "c:\")
If sPath = "" Then
MsgBox "Ms Office not found!", vbExlamation
Else
MsgBox "File full path = " & sPath, vbInformation
End If
End Sub
'----------------------------------------------------------------------------------
Уж полночь близится, а аффтар все ни жжот!