Microphone Volume Problem In Garage Band


I am trying to use a microphone to record an instrument/voice into Garage Band. The microphone DOES record but I have to yell into it for the recording to be heard. The microphone is very cheap, however I don't have a problem with volume when I use it with my Guitar amp (I don't know if that means anything or not.)

I have set my Line In system sound preferences to "audio line-in" and set the volume to the max, but I still get this problem.

Do I just need a better Mic? If so, what would be the best options for recording a (non electric) instrument.
It all depends on what type of mac you have. I want to say this load and penetrating, modern Macs DO NOT HAVE A MICROPHONE PORT!!!! They have a superior audio LINE-IN port. What is the difference? In as few words as possible to explain the difference, the quality of recordings. In simple terms a microphone port because it has power on the port, a line-in port does not. A Microphone hurts recording music with power behind it (i.e. turn tables, cassette recorder, etc.). A line-in port is higher quality and has no power on the port for clean recording through it.

So a non-powered microphone will will act like what you are talking about. So you have two choices, buy either a device like the an Griffin iMic and use you current Mic, or buy a USB microphone from your local electronics store.
With the right cable adaptors a DI box would also work. Like Satcomer said, you basically need a pre-amp to bring the signal from your microphone up to the right level. Same goes for plugging a guitar straight in. Basically just don't plug stuff like that straight into a line in. It won't work/will be rubbish.