Create virtual servers, using the resources of multiple physical servers

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http://serverfault.com – I am a newbie and I need some help. I want to create a virtual network infrastructure that is sharing the resources of 3 physical servers. I want to create a resource pool, containing my three physical servers. My virtual network is going to have only 6 VMs. I will be using Microsoft Server 2008 standard edition. I am wondering what software should I use to achieve this? Also, is it necessary to use shared disks, when creating clustering? From most of the tutorials I saw, the requirement is always to connect shared disks (LUNs), but I want to use only the disks of the servers. (HowTos)