At this point, I would only go with components that are on the HCL... Items like the RAID controller (hardware RAID, onboard controller most of the time use software RAID), Xeon 5300, Xeon 5400 or higher/newer processors, SAS hard drives all around. Video cards are irrelevent since anything will do the job as long as it has the correct connection for your display (I went with the cheapest option when getting my host). 8GB would be a bare minimum amount of memory, since that fills the memory slots in the cheap motherboard you selected, that's a huge red flag. You'd need a REAL NIC too, since the onboard (realtek) is unsupported.
You'd be better off picking up a reconditioned Dell Precision Workstation 490, 690, T5400 or T7400 or even one of the R series (rackmount workstations) than using what you've listed. Especially since you can get them with dual Xeon's (dual and quad cores per socket). They also come with 8 memory slots (at least) so you can easily go beyond 16GB of RAM. The onboard Broadcom NICs in those systems ARE supported. Of course, you'll want to install additional NICs.
Look on http://outlet.dell.com or http://outlet.us.dell.com inside the US... I just did and found several R5400 units listed that wouldn't need much modification to make a valid ESXi 4 host... I'd guestimate that for under two grand you can have a quality ESXi host that way...
VMware VCP4
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