⇒ Update: VMware ESXi 5.0 on ASRock ION 330

The ASRock ION 330 has a NVIDIA MCP79 chipset which is not officially supported by VMware's ESXi 4.1. However you can modify the AHCI driver and create a custom installer using mkesxiaio. If you do not want to modify the driver yourself you can get my pre-modified one here. Just make sure to switch to AHCI mode in the BIOS.

Also by default the ION 330 has only 2GB of memory that is shared with the integrated graphics solution. Thus, to use the system with the pre-installed memory only, the amount of shared video memory has to be reduced in the BIOS to 32MB.