Programs Quitting (without errors) and kernel panics!

Question

I think my iBook is dying! I recently switched over to a G4 iBook, 1.42Ghz with 1.5GB RAM. I am running 10.4.9 and keep it consistently updated.
Starting two nights ago, Safari, Mail, and Roxio's Toast have all quit instantly, out of the blue, with no error message popping up. At some points, I click on the icon in the dock, it bounces, then it stops and never opens. Sometimes it opens for .5 seconds and then closes again. Sometimes it opens just fine!
On top of that, I had a kernel panic this afternoon as well. I am afraid of this being on its last legs!!! Any help? Here is the kernel panic info:
panic(cpu 0 caller 0x0021C8F4): btreejournal_modify_blockend: about to write corrupt node!
Latest stack backtrace for cpu 0:
Backtrace:
0x000952D8 0x000957F0 0x00026898 0x0021C8F4 0x0021CA9C 0x002431EC 0x00244C04 0x00241BAC
0x0021F148 0x0023B72C 0x0023AE4C 0x000FC92C 0x000EE3FC 0x002AB7F8 0x000ABB30 0x00000000
Proceeding back via exception chain:
Exception state (sv=0x38D07500)
PC=0x9001B7CC; MSR=0x0200F930; DAR=0xE02F5000; DSISR=0x42000000; LR=0x0000E9B4; R1=0xBFFFE790; XCP=0x00000030 (0xC00 - System call)
Kernel version:
Darwin Kernel Version 8.9.0: Thu Feb 22 20:54:07 PST 2007; root:xnu-792.17.14~1/RELEASE_PPCModel: PowerBook6,7, BootROM 4.9.3f0, 1 processors, PowerPC G4 (1.2), 1.42 GHz, 1.5 GB
Graphics: ATI Mobility Radeon 9550, ATY,M12, AGP, 32 MB
Memory Module: DIMM0/BUILT-IN, 512 MB, built-in, built-in
Memory Module: DIMM1/J7, 1 GB, DDR SDRAM, PC2700U-25330
AirPort: AirPort Extreme, 405.1 (3.90.34.0.p18)
Modem: Jump, V.92, Version 1.0
Bluetooth: Version 1.7.14f14, 2 service, 1 devices, 2 incoming serial ports
Network Service: AirPort, AirPort, en1
PCI Card: pci106b,4318, sppci_othernetwork, SLOT-B
Parallel ATA Device: MATSHITADVD-R UJ-845E
Parallel ATA Device: FUJITSU MHV2060AT, 55.89 GB
USB Device: OneTouch II, Maxtor, Up to 480 Mb/sec, 500 mA
USB Device: Bluetooth HCI, Up to 12 Mb/sec, 500 mA
USB Device: Apple Internal Trackpad, Apple Computer, Up to 12 Mb/sec, 500 mA
USB Device: Hub in Apple Pro Keyboard, Mitsumi Electric, Up to 12 Mb/sec, 500 mA
USB Device: Apple Optical USB Mouse, Mitsumi Electric, Up to 1.5 Mb/sec, 100 mA
USB Device: Apple Pro Keyboard, Mitsumi Electric, Up to 12 Mb/sec, 250 mA
HELP! I would love to go buy a MacBook now, but I can't afford it quite yet.

Answer 1

Thanks John!
I am having the original install discs sent my way - I am a current college student so I did not have them with me! (Go figure!)
I will definitely attempt this.
I have now, however, found one more thing that is wrong. My audio is not working! When I go to change the volume, the speaker icon comes up, does nt change the level and also now has a new circle with a line through, indicating there is no audio? I checked the Audio settings in System Prefs and it is showing there as being no Audio Output. Again...HELP!
Thank you again, John, for being kind and helpful!