Tagrineth, if you're going to throw around "reading comprehension" I would suggest you learn a little more about computers before doing so.
Windows 7's built in Volume Mixer (the directions I just told you...) has the power to mute specific programs, even JUST FFXI. It will NOT mute your entire system.
By clicking the program's speaker icon in Volume Mixer it is marked with asign which mutes the program.
And Meyi you are correct, so that would be a nice request now that you mention that.