If you are looking to refresh your vSphere home lab, definitely consider looking at the Mac Mini, especially when the 16GB DIMMs are available you can get up to 32GB.

I found a great article form VirtuallyGhetto blog for a step by step on this experience.

In some lines the procedure is:

What you will need:

Step 1 – Extract the offline bundle “tg3-3.120h.v50.2-offline_bundle-547149.zip”from Broadcom zip file

Step 2 – Use Image Builder to add the Broadcom driver and create a custom ESXi 5 ISO (steps taken from this VMware KB article)

# Add the ESXi 5.0 Update 1 Offline Bundle
Add-EsxSoftwareDepot “C:\VMware-ESXi-5.0.0-623860-depot.zip”

# Add the Broadcom Offline VIB
Add-EsxSoftwareDepot “C:\tg3-3.120h.v50.2-offline_bundle-547149.zip”

# Create a new Image Profile (in example, I’m using the full version w/tools)
New-EsxImageProfile -CloneProfile “ESXi-5.0.0-623860-standard” -name “ESXi50u1-Custom”

# Add the broadcom driver to our Image Profile
Add-EsxSoftwarePackage -ImageProfile “ESXi50u1-Custom” -SoftwarePackage “net-tg3”

# Create an ISO from our custom Image Profile
Export-EsxImageProfile -ImageProfile “ESXi50u1-Custom” -ExportToISO -filepath C:\VMware-ESXi-5.0u1-Custom.iso 

Step 3 – Plug in a USB key into your system and run UNetbootin which will take the custom ISO we just created and make it bootable on the USB key

Step 4 – Finally, power on your Mac Mini and plug in the USB key. You can either hold the “Alt” or “Command” key while the system is booting and select the EFI volume OR just plug the USB key and the ESXi installer should automatically start up.

See more details on this at VirtuallyGhetto