This isn't specific to Mac or Windows.
I'd like to be able to leave my headphones plugged into either my PC or Mac, however I don't want the sound to be muted.
I just find it inconvenient plugging in and out my computer all the time.
Is there a way to do this, switching the headphone jack plug on and off?
Sure you can do it, but I would think that a better idea would be to get something like a M-Audio Transit and use that to feed sound to your system via USB.
Um...I'm not sure I understand your problem. When I plug in my headphones, I get sound both from them and the speakers without doing anything special. Isn't that so for everybody?
yes.. ojalord.. that makes two of us.. atleast here till now..
I'm confused. What exactly are you getting at?
I'll need to check again, good chance I've been a spanner.
I'll update later, if I'm going to be eating humble pie or not. 
Um...I'm not sure I understand your problem. When I plug in my headphones, I get sound both from them and the speakers without doing anything special. Isn't that so for everybody?
actually, on my system i have a headphone jack at the front, plugging anything into it cuts the signal to the speakers (which are plugged into my sound card at the back). i find that useful.
actually, on my system i have a headphone jack at the front, plugging anything into it cuts the signal to the speakers (which are plugged into my sound card at the back). i find that useful.
I too have special headphone and mic jacks (and two usb ports too) on the front. That is where I normally connect my phones and it never cuts off the speaker sounds. So, I get to keep my phones plugged in permanently and just switch of the speakers when using them (the phones).
@Painkilleryusuf, your Avatar makes two of us too, 
I wasn't going mad, when I plug in my headphones my speakers do cut out, the same as slewed. Unfortunately I don't find that useful. I'd like keep the headphones plugged in all the time and maybe just use a hotkey to switch them on and off.
If anyone has a clue how to do this on a G4 iMac please let me know.
Cheers
It all depends on if they used a N.O. (normally open) jack or a N.C. (normally closed) jack. Most jacks are set up to turn off the speakers when you plug in the headphones. Hotkeys and/or software cannot trump a physical connection. USB is your best option.
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