Output Microphone Directly To Speakers

[pureelite1]

I plan on making some announcements during an event we are holding and have a microphone with a USB connecter so it can connect into the USB port of my laptop. However i cannot figure out a way to output whatever is being spoken into the microphone simultaneously through the speakers we have connected in the audio output jack of the laptop so that everyone can hear. Any software or settings that would allow me to do this? Urgent help is required the event is tomorrow. Thanks,

Details:
Operating System: Windows Vista

I would also like to know how to do this type of thing with my iMac running OS X Lion

 

[shwc]

On the mac side:

LineIn is a free utility application from rogue amoeba that will pass audio from mic to speakers (etc.).

 

[samh]

I plan on making some announcements during an event we are holding and have a microphone with a USB connecter so it can connect into the USB port of my laptop. However i cannot figure out a way to output whatever is being spoken into the microphone simultaneously through the speakers we have connected in the audio output jack of the laptop so that everyone can hear. Any software or settings that would allow me to do this? Urgent help is required the event is tomorrow. Thanks,

Details:
Operating System: Windows Vista

I would also like to know how to do this type of thing with my iMac running OS X Lion

On previous versions of Windows you could mute/unmute/turn up the volume of the microphone input using Advanced settings in the Volume Control applet (on playback side). Also make sure that Mic was checked as input source and turned up on the Recording side.