T500 Mute Button

[lagged]

My mute button toggles mute on and off. I prefer the style of my old T42 where mute could only turn mute on, to unmute you used the volume buttons. I could turn my laptop on and just hit the mute button and know it won't make any noise. Now its guess work on the T500.

Can I revert the functionality back to that of the T42?

Thanks!