I have the Logitech S530 keyboard/Mouse combo and I've been using their products for a very long time with Windows. Almost all the keyboards I've used on Windows previously have had media keys for controlling volume as well as play/pause and skipping back and forth.
The S530 also has these keys, however these keys seem to be hardcoded for iTunes. I'm not sure if this is a keyboard issue or an O/S issue. Under Windows, whichever the active application is (Media Player, PowerDVD or WinAMP etc.) would utilize thise buttons. So for instance, if I'm watching a movie using PowerDVD, the pause button on the keyboard would pause the movie. If I'm using Windows Media Player, it would skip the track playing on that.
With the S530, if I have Quicktime on and press the play/pause, iTunes gets loaded and starts playing- very irritiating. Again, not sure if this is a keyboard issue or an O/S issue. Would love to hear from others.