Using external microphone to record on MacBook Pro

I have a new 17" MacBook Pro. I also have an old-ish Audio-Technica Pro 24 stereo microphone. The microphone was actually bought by my parents to record my brother's band's concerts. They hooked it up to their camcorder, and it seemed to work fine for them. My brother and his band all went to different states for college, so now I've inherited the now mostly-useless microphone. I'd like to hook it up to my MacBook and use it to record my voice, but nothing seems to work. I've replaced the battery. I have it plugged in to the audio input jack (looks like a circle with two triangles pointed in to it). I go to System Preferences>Sound>Input and click Line In, but there's no sound registering from the microphone. Oh, and I have the microphone switched "On." So, is this a problem that's solvable, or is my microphone just not compatible?

Hi, the input you are referring to is a line input and not mic in.

You will need to buy an external sound card to use the mic. Try the griffin imic if you need something cheap.

Great, thanks for your help.

Audio In

I just bought a MacBook Pro. I see the Audio In plug on the side, but I'm not quite sure what it's good for. What is Audio In commonly used for on laptops? I thought I could plug in a mic to it, but apparently not...I'd need an external sound card like Griffin's iMic (which is USB, not Audio In) to use a mic. So anyone? Anyone?

I would recommend getting a USB mic, the Blue Snow ball is a good one and what I use is the Samson C03 USB microphone. The C01usb is a good option also.
The Griffin iMic is certainly a good option too. I use one with my MacMini to which I have connected a smaller 1202 Behringer type mixer which supplies my Behringer B2 mic with phantom power.

@wizardgold
Mac 20 Questions Podcast

I have a follow-up question to this. I do a podcast using Garageband. Up until now, I have had all my audio from my sound board go into my MacBook line in outlet. I just ordered a USB condenser microphone which obviously plugs into the USB port. Will the Macbook recognize both audio signals simultaneously? In other words, when I record in Garageband, will the audio signal from my line in as well as my new USB microphone be recognized? When you go into the Audio/MIDI settings, the only options are line in and built-in mic. I'm not sure if USB is completely separate from these two choices. Thanks!

For anything going into the "line-in," you'll need some kind of preamp to boost the line level so it's nominal for recording.

I just picked up an ART Tube MP Original, tube mic-pre (well, getting it today). Plug your mic/guitar/bass into the Tube Pre, THEN into the line-in, and you'll get a really, really good sound/usable signal.

I'll post more on this once I actually have the Pre setup and working, with sound clips.

External Microphone not working

I have an external microphone that was working properly, and no longer is. I've tested the microphone in a windows laptop, and it's fine. I believe the problem is related to the most recent upgrade. When I go to System Preferences->Sound and switch to the internal microphone, the levels are fine; with the Line In chosen, there is nothing even with volume at maximum; again, it worked perfectly previously. The external headphone does switch as expected