Memory: I never checked. My PC never uses it's 2 GB of RAM anyway, so I don't care about memory usage of the program. But if you want to know, just run task manager and compare the memory usage of these 2 programs in a few scenarios. Can you tell us the outcome of your experiments.
Generally, Firefox is considered somewhat more secure than IE. But the browsing habits of the user are the most important factor in security.
I am sometimes confused about which web browser to choose,I just wanted to have a comparison between Firefox and IE. Does IE uses more memory then firefox?
My other question is that is IE more secure then firefox?