If you are a VMware vSphere/ESX customer hopefully esxtop is something you are familiar with...if not please get familiar. Esxtop is top for esx...get it? Wondering how loaded your ESX host is? Curious if there are performance issues on your ESX host or underlying infrastructure? ESXTOP is your friend...and now we have a document from VMware to help interpret the wealth of information that ESXTOP gives us. http://communities.vmware.com/docs/DOC-11812
Now all you need are some thresholds to compare those statistics against.