kernel panic on start up

i was getting several kernel panics per day on my powerbook, so i reformatte the hard drive and reinstalled the os, but now it won't even get past the start up screen without giving me a kernel panic error. i had read that ram can cause this problem, so i took some ram out of another one of my powerbooks and it was doing the same thing, so i think i can rule that out. i also checked to see that my airport card was properly seated. any suggestions? this is one of my primary computers, so i really need to get it up asap. thanks.

steven tader

powerbook g4 500
768mb ram
30gb hd
airport card
combo drive

i can boot from my cd, so would that rule out hardware problems?

i did run disk utility from the cd, and i repartioned the drive and repaired the permissions, but it didn't help, i just went and got norton system works so hopefully that will help. i am going to try to set the problematic powerbook up as a target drive for one of my other powerbooks and try to give it a mor thorough reformatting and reinstallation. i am also going to try to put panther on it instead of jaguar. if this is in fact a hardware problem, what is it and what cost should i expect to repair it?

i didn't use system works, because when i installed panther, everything went smooth and the problem seems to be fixed. from my experiences with this powerbook and annother one of my g4's, jaguar is not quite up to par. thanks for all the suggestions.