I've been working on setting up a POC for XenDesktop 5.6 and provisioning machines with MCS (machine creation service). I ran into a problem where the machines I provisioned were trying to PXE boot, as if they were configured to reach my Citrix PVS server. Here is the setup: I have a Win7x64 template in VMware, I have multiple DDC's going through an F5 load balancer. I have both PVS and MCS in the same environment. There is a rule in MCS that the C drive for the template must be on "hard disk 1" within VMware in order for MCS to provision machines correctly. I did have this setup correctly.
Here is the problem I found. My template was using the new "EFI" bios instead of the traditional BIOS. EFI is the next generation BIOS in vSphere 5 for version 8 virtual machines. Since the hard drive device ID is handled differently in EFI vs BIOS, MCS in citrix did not know what device was the C drive upon boot, causing the next device in line (the NIC) to PXE boot. After I built another template with the traditional BIOS (still on version 8 hardware), MCS was able to correctly provision machines.
For an overview of the vSphere 5 EFI (extendable firmware interface) bios, check out this YouTube video.