I always called these fatal errors...but kernel panic sounds a lot cooler and less depressing.
When you did the install, did you do it in the form of a 'cold install' from the original OS X disc included with the comp sale, then update OS X from online, then add all other programs?
How did you add the programs? I ask this because if something was corrupted and you brought it over using migration assistant, TM or CC, you are still going to have a corrupted file which is producing something OS X does not recognize and gets confused by.
Are you using any unusual or '3rd party' software?
When it happens, are there any processes that have consistently been opened at the time?
If it keeps happening, I would try a cold install of OS X only and no additional programs to try to get an idea of the source. If it does it then, either way it is on Apple as you have a bum copy of OS X or something is indeed wrong hardware wise. If you ship it to them, put the normal RAM back in and HD because they may replace them by default and that would suck if they tossed your higher end HDD.