According to the original owner of the computer, he stated that it specifically WAS the way Vista reacts to large amounts of memory.
but that dosnt make sense. because vista (just like win7) has a 32 and 64bit version.
32bit's use up to 3.4gigs, and 64bit uses up to 128gigs.
its just a staple of picking a version of windows.
if you KNOW its ram issues because the blue screen implies so, then maybe you are using 2 different brands/incompatible sticks to each other.
or the ram itself is just shot. like harddrives, ram can just stuff out one day. its one of the most common computer parts to just die (or one day be forgeted up and cause crashed) suddenly.