Question regarding Server CPU/RAM Utilization..

I have a small business file sharing server setup. I have about 4 employees, 2 actually using the server all day editing/opening/deleting files simultaneously.
What causes the CPU to jump up if you were to have a filesharing server?
What is the reason that you do not need to have a lot of RAM for a filesharing server?
Answer #1
Because most your resource usage is disk IO (and network IO), since your just reading and writing to files (over the network).
Answer #2
Because you are not using http://en.wikipedia.org/wiki/Zero-copy
http://en.wikipedia.org/wiki/Remote_direct_memory_access