GarageBand Problems

First off, GarageBand is friggin' sweet for you aspiring amature recording artist...but for some reason, just recently, I am unable to get any sound from my guitar when it is plugged into the audio input jack, using a 1/4" to 1/8" converter of course, in the back of my PowerMac G4 dual 1.25Ghz. But, when I check to see what going on in "sound" under system preferences, it shows that my mac is receiving a signal from line-in. Suggestions?

First in your garage band preferences, make sure "built in audio" is chosen under the audio/midi tab. Unless you are using an audio interface, any sound app will use built in audio (sound manager) If using an audio interface, you would choose that instead od built in audio.
Next in your G4's System preferences click the sound tab and make sure your input and out put is set to built in audio.
Also, when you create a new track "real instrument track, make sure the proper output is set there as well and "monitor" is turned on in the pop up window when you create "new track".
Lastly make sure the solo buttons on other tracks is not on.

That should do it dude.
You should get an audio interface for that guitar though. You will get alot better results if you do...and a preamp.
I use an M-Audio firwewire Audiophile 2496 and a Studio projects preamp but there are lots of models, brands to choose from in all price ranges.
Good Luck,