Hi,
CPU Limited = http://www.virtualclouds.co.za/?p=526 (At the bottom of the page)
CPU Contention = This look at the pCPU Contention...thus how long the scheduler had to stop VM's so that other VM's could run due to not enough pCPU cores being available (Something like that:-) )
Disk Demand = in general the Demand metric is made up of diff other metric's...more than that I cannot remember
Network IO Usage = How much Kbps the vNic is using.
Hope that helps
Hugo Strydom
www.virtualclouds.co.za
Hugo Strydom
Blog : www.virtualclouds.co.za
Twitter : hugo_strydom