Hi LucD,
Thank you for your quick reply.
I've just tried that and have successfully managed to pull the stats I was after which is fantastic. You were correct - I was getting confused with the values that can be derived from the 'cpu.usage.average' counter.
I'm the process of reading your "PowerCLI & vSphere statistics" and I am finding that really useful as well as I'm just starting out.
Thanks again for your reply - I can now build on that to get the stats I need for the entire estate.
M.