Dead G4 iMac: Suggestions?

My parents 4+ year old first-gen G4 iMac just died rather abruptly.

After some basic testing, the hard drive is fine--I can (and did) get data off of it when running in target disk mode. All the other firmware stuff seems to run ok, too--I can get into OF and do resets, and the boot selector is working.

...but as soon as I try to start up from absolutely anything, Kernel panic. Never even gets past the grey apple. Tried the internal drive, an AppleCare TechTool CD, a Tiger DVD, and even the Tiger disc in an exteral Firewire drive--all start to boot, then KP. The panics actually cough up text, and the first line of the panic looks like it says "no driver for PowerMac 4,2" (though it scrolls by pretty fast), which makes it sound to me like either the processor is dying/dead, or there's something seriously wrong with the motherboard (though no so wrong that OF doesn't work, and it can still communicate with the USB and FireWire ports and the ATA bus that the hard drive is on well enough.

It's a very crusty computer (I have NEVER seen a keyboard that ugly, and they don't even smoke), so I'm not sure it's worth the expense of having a pro fix it, but I'm wondering if anybody's seen a similar failure or have any suggestions other than the obvious.

Since if it's getting recycled/ebayed anyway, I might as well goof around with it while I've got it cracked open to pull the drives--they're both good, and I installed a brand new optical a year or two ago.

Now, now, if I was going to go berserk modding the thing, at the very least I'd want to use the built-in LCD (if for no other reason than it's working fine). That said, I can get a used motherboard for the thing for a couple hundred bucks, so that'd be a lot cheaper and less hassle than tearing apart a perfectly good mini.

Not that it wouldn't be cool to have an Intel-based "G4" iMac, but to do it proper you'd have problems lining the ports up correctly, and you'd need to vent air out the back end, and you'd need to modify the CD area for the slot loader, so by the time you were done you'd have to hack the whole back of the iMac off and pretty much just shove the mini in there with no case on, and you'd still have an ugly cable for the screen running out to the port and back in.

I wouldn't be surprised if there are clever ways around these issues for those very handy with a soldering iron, but I'm not about to spend that kind of time and effort potentially breaking a perfectly good refurbished $500+ computer.

Bad RAM

Definitely good suggestions, aquajet. I'd already tried starting "bare", with no success, and was planning on swapping the RAM for another stick when I had it cracked open.

...except I'd forgotten that it also had some RAM in the mcuh-easier-to-get-to lower slot. Which turned out (thankfully) to be the problem.

Actually, I suppose the slot could be bad, but sadly I don't have even a little stick laying around to test with, so I guess it's just buy a replacement and hope it's only a bum stick.

I'm a tad surprised, just because it didn't behave quite like I would have expected for bad RAM (and the failure happened so abruptly), but the SODIMM is toast and everything else appears to be in perfect working order.

Small miracles, I guess. Also makes me a bit glad I don't buy Edge RAM (and no warranty luck, since it was bought secondhand with that stick already in there--that's why I didn't realize there was one in the lower slot).