I was looking for a good way to see in real time how my server was performing.
I used top to see the performance but it can be quite difficult to see the total picture of your entire server.
Top separates performance down to each process but not as a system whole.
After some web surfing, I came across a forum that suggested i look at htop.
htop is pretty decent - it basically gives you top but also a overall gauge like bar right at the top
which shows you the current total memory usage as well as the current total cpu usage.

Website : http://htop.sourceforge.net/