If you install the new version of Ubuntu 11.10 Oneiric Ocelot you will notice that it comes with Unity installed in order to make a better OS experience.  That could be very well true, but I do like to see my system monitor and see how my PC is behaving.  Now, it can not be easily done with unity, but if you would like to do it, go to the link below and you will be able to find steps by using PPA in order to get your system monitor on unity.  Also, if you don’t like unity you could go back to gnome, but that is something different that is not being cover in this article. 🙂

Source http://www.linuxnov.com/system-monitor-indicator-for-unity-panel-in-ubuntu-11-04-natty-narwhal/