AFAICT this is the simplest way to tell if Itunes is playing.
Code:
ControlGetText, plyStat, Button10, ahk_class iTunes
If plyStat Contains pause
msgbox, Itunes is playing.
else
msgbox, Itunes is not playing.
This works in Itunes 8.1.1.10.
Looking for a way to return the status of WMP

.
edit:
Looks like your going to have to use COM to figure out wheter or not WMP is playing.
See here:
http://www.autohotkey.com/forum/viewtopic.php?t=33686
IMO this is hell just to find out whether or not its playing and results will probably be OS and version dependent.
You could always cheat by getting the color of a pixel on the play button.
Good luck!