I don't have electrical noise on mine, but when I hook up my headphones, the speakers on the laptop don't shut-off. I degraded to XP, but don't remember if Vista did this. I would deduce mine is hardware, but I am not too sure.
Has anyone had issues with the audio drivers? I am having a weird issues with my laptop when I hook up headphones to the laptop, the desktop speakers won't shut-off. I degraded the laptop with Win XP SP2.