vSphere 4.1 and HA

Hello,

I have a virtual center vSphere 4.1 with 2 clusters and 6 ESX 4.1.

In the first cluster I have 4 ESX, Blades HP 460c G6, 2 with 62GB RAM and 2 with 64GB RAM. I would like to ask you what the best configuration for HA and specially for Admission Control Policy. How many hosts do I have to select for Host Failures Cluster tolerates?

Thanks in advance.