Kernel Panic, now no Startup, PLZ Help

My dad got an iMac OS 10.6.4 and it has acted up lately and now died. It had some kernel panics, and dad was going to back up today but after a restart it won't start up.

I tried to update the software, but on restart it said error so restarted again, but I don't remember if it then installed correctly or just went to normal.

I have searched the web for solutions but none work. Ive done the boot from install CD but the utility couldn't repair, and the HD didn't even show for re-installation.
Tried disconnecting all peripheral devices besides an apple keyboard and mouse - no luck.
tried the safemode, didn't work. Started in Verbose or single-user, and saw it had command to repair.

Reseated the RAM, but I think its a directory error. I couldn't find how to fix this besides backup and restore the disk, but we dont have a backup. So kinda in a catch-22.

Any ideas? thoughts? or terminal commands to use to help start up?
Is there a command to only start up with finder - like if other applications were running and it wants to restore them on startup, to stop those and only launch finder?

 

Idk if the logic board is really the problem.

Cause when repairing, it came up with overlapped allocations and such. So having a new logic board wouldnt fix that, would it?

Could you use Diskwarrior to fix that kind of thing?