Gnome-system-monitor shows, under resources, three things, namely CPU, Memory and Network History. Is there a Lubuntu equivalent which shows me these things? As far as I've noticed, Lubuntu has Task Manager but this only shows CPU and memory usages, without any history charts and without any network information.
You can install the gnome-system-monitor on Lubuntu:
If you are looking for a lightweight alternative you can use Conky:
More possibilities you can find here http://www.upubuntu.com/2012/06/list-of-best-system-monitoring.html