DISK TOO SLOW on a POWERBOOK G4!

Hi can someone pleeeeaasse help me quick!!! I have just spend loadsa dosh buying a midi keyboard, mic and a fast track audio device for my powerbook! I have 34gb free on the hard drive, 256mb of memory, and a 1.33ghz powerPC G4 processor. The operating system is mac OS X 10.3.9! However, when i try to record guitar (and this is the first track in so who knows when i'm on the 10th what would happen) it just says 'disk too slow' about a minute to a minute and a half into the recording! I've read the solutions saying buying a external hard-drive is the way to go - but i can't afford to buy one if it won't help. Basically I want to be able to record quite a few tracks comfortably can you tell me what i need to buy (ie firewire harddrive) or what i need to do (ie install garage bands 2) to increase my performance and stop these problems.Thanks!!!!