Well looks like you have two different errors - Bugcheck 1a ( MEMORY_MANAGEMENT) and Bugcheck 3b (SYSTEM_SERVICE_EXCEPTION)... both usually caused when memory pointers are not refereneced properly.
I would suggest you do a
memtest on each RAM at each slot for atleast 7 to 8 passes...This could take some time.
If you are getting errors that would mean you have a problem with one of the RAM stick.. if not.. then i will let you know the next step.