I have a new lump of hardware on my desk, intended to be a household server. It's basically an Asus P5Q Pro motherboard, with a couple of SATA disks. With a few gig of RAM and a dual-core processor, it is intended to be a virtual machine server, running a firewall, MythTV/media archive, and some public sites.
VMWare ESXi was going to be the base OS; it's “free as in beer”, it's going to be used on some of the company systems I'm installing this year, it provides a nice and secure base OS and virtual networking that would make separation of different guests easy.
However, I didn't check the hardware compatability of ESXi before getting all enthuiastic. VMWare do use Linux under the hood, but I guess in the interests of reducing support issues, have only kept drivers for the most enterprise-class devices that they expect to see in the datacentre.
This means that although the P5Q has a supportable SATA device, by default ESXi doesn't recognise it. You have to hack both the ESXi installer, and the installed image to get it to work.
Also, ESXi does not recognise the onboard Atheros network interface, which means that it cannot be available for any of the guest machines. I would have to buy a supported NIC for my machine; that's basically an Intel one. It would have to be PCI-Express, as those are the only ports free. That puts the price up to around 40% of the entire of the rest of the server.
Sorry, ESXi 3.5. If you get wider hardware support, I may install you. Otherwise, it's off to Ubuntu and KVM …