The way to find the path of the [u]active</u> Excel file is pretty straightforward:
strPath = Activeworkbook.Path
Now, Stan's way can be used to get the path of anyone of the open Workbooks.
Suppose "File1.xls" is one of the open workbooks.
Code:
Dim strFile as string, strPath as String
strFile = "File1.xls"
strPath = GetFilePath(strFile)
Function GetFilepath(ByVal strFile as String) as String
GetFilePath = Mid(Workbooks(strFile).FullName,1,InstrRev(Workbooks(strFile).FullName, "\") -1)
End Function