generally its enough to fix any BSOD you might have. Memory dumps can grow to several gb in size, minidumps only 256kb, slightly easier to upload and sort through I assume.
Minidumps should be easier to work with. Generally what sort of system errors will create a memory dump? I notice that in Event Viewer that the source is usually 'BugCheck' and that they're usually event 1001.
What is the difference between a BugCheck and other errors you might see in Event Viewer?
BSOD create memory dumps, I am not sure what else does as there are kernel dump files that grow over time so i think windows creates reports on most operations and they create dumps.