Hi,
Just before begin, you need to check the VMware HCL :VMware Compatibility Guide: System Search
And then if you want to install an ESX4 you can check this : https://www.vmware.com/pdf/vsphere4/r41/vsp_41_esx_vc_installation_guide.pdf & this : VMware KB: Installing ESXi/ESX 4.1 and vCenter Server 4.1 best practices
Regards,
Julien