He just said that he doesn't know much about computers, and you just gave quite an explanation. I know something about computers and I still had to read slow in order to fully understand, jaja .
Please, don't get mad. I DO appreciate your answer, it is very educative.
An easier answer (maybe not the best one, but kinda easy):
If you're planning to use a lot of programs at the same time, or some heavy software, get 4GB.
Even if you won't use several...