I've been using garageband casually for about a year now, and recently (within the past 2-3 months maybe) I've been getting this sort of crackly static in the background when I record, and have had to adjust the screen of the laptop (where the mic is located) back and forth to try to frizzle it out. Its never completely gone, just quieter. This is version one of Garageband, an iBook G4 from late 2004 or maybe early 2005. This has only been going on since I've been recording loud drums, so I wonder if all that aural abuse on a little mic could have anything to do with it.

Any Ideas?

try disconnecting the iBooks psu and running from battery - i found my effects pedal power supply causes interference when my Macbook operates on mains power...

I've tried that. Absolutely no difference, and nothing to make me think that would be doing it.

I know that garageband itself, as a program, isn't causing the problem. I've tried using Audacity on the same iBook under the same circumstances and the static was identical.