I had a problem when I tried to install ESX 4 U1 on HS22 7870B3G via AMM (Advanced Management Module).
The boot process was ok but stops after 22% in installation process when loading the network drivers.
The built-in NIC drivers from ESX cd breaks connection to AMM.

Solution : Download the latest driver cd for Broadcom NetXtreme II from VMware.com and add this driver before the installation process.