I think that if you use the "archive" feature, it will create a "zip" file that can be opened by Windows users. In OS 10.3.9 (which I use) you highlight the file then go file->"create archive of [file or folder name}". You can easily email the new zip file. Not sure if it changed in Tiger--or if I'm correct that the zip file can open in Windows--but I do think it can.