That error message is due to a kernel panic. It could be either software or hardware, but generally they are due to hardware problems and it is the easiest thing to check. Do you have any USB devices attached? If so disconnect them and see if the problem ceases (if you have a hub, start by removing that from the equation). Insert your install disk and run the hardware test - this may tell you if you have a problem somewhere. If you have installed any additional RAM, remove it - you could have a bad RAM stick which will definitely cause this problem. Even if you haven't installed any third party RAM, try removing one stick at a time to see if the problem goes away (obviously, this only applies if you have two sticks inserted - if it is just one, you will have to rely on the hardware test to check it for you).
Launch Font Book and verify your fonts (from under the File menu) to see if you have any problem fonts installed.
Did you use Migration Assistant to transfer from an old PPC Mac? If so, try clearing your caches and looking for potential troublesome software or preferences that got transferred over. What software have you installed yourself? Is it possible that you are using some that is not yet Intel compatible? Make sure you are using the latest updates. If you are using any system hacks or third party plug-ins, disable them. Make sure they are the latest versions. If they are not intel compatible yet, disable them permanently.
If none of that helps, get in touch with Apple.