No idea about PCs but it should 'see' it as soon as it goes into the Mac, although it won't appear on the desktop it should appear as a little icon in the menu on the top left of the iTunes window.

If not go to 'About this Mac' in the Apple drop down menu (top left), then 'more info', then see if USB appears, if so click on it and see if it knows it's an iPod/Phone. If not see if you can borrow someone else's cable and see if yours is dodgy.