If hes just sharing stuff between two computers why not use Outlook for Mac with Personal folders and just copy the PST file between the two to "sync". I.e. when he goes away copy the PST file to his iBook from his G4. You could use the same idea with any e-mail program with a calendar.. I think even Eudora has a calendar now. Exchange seems overkill in this case.. it's either a waste of money or another "legal risk" depending on how you acquired it.