Review - Vmware ESXi

I have played with Virtualization software for awhile now.
They say that most servers are under 10% utilization nearly 95% of the time. Network Admins like to buy a server for every application to keep them seperate and avoid software conflicts and these servers collect and are grossly underutilized. We have been using ESX at work for years and have found that they are very stable and cost effective. We run mostly test servers on ours, however we have a few live servers, even Exchange running on an ESX server.
Vmware has been giving Vmware Server away for awhile now, and I just found out that they are now also giving away ESXi.
Vmware server runs on top of a normal operating system such as Windows or Linux. You install it like a normal application and it allows you to install and run Virtual Machines inside that operating system. This is very cool and I have used it quite a bit to play ith operating systems without having to provide a physical computer. This method of serving virtual machines works, but is not optimized for speed or reliability and therefore shouldn't be used in a production environment.
ESX and ESXi are what they call bare metal vitrualization servers. They run as their own skinnied down operating systems and provide an interface on top of this to install and manage Virtual Machines.
ESXi is ESX wiht a few features removed or unsupported compared to ESX. However, ESXi is free and we can work around its limitations.
ESXi is made to be run off of a flash drive or flash memory built on to a server's motherboard. Dell makes ESXi servers. This way, the OS doesn't waste hard drive resources and the functionality is as easy as possible for an administrator. Just boot up the server and add or mamage VMs from the interface. It also comes as an installable version similar to full blown ESX. This is the version I decided to run.
I got a 1 tb hard drive, Intel motherboard with dual core processor and 4 gigs of RAM to install and run this on. I am running in at home and in my bedroom next to my main computer, so I want speed, low power utilization for 24 hour use and quiet operation.
I decided to use the following hardware:
Asrock motherboard with gigabit ethernet and 8 gigs max RAM
Intel Core2 2.5 Ghz CPU
Western Digital WDGWD10EADS Green Power 1 TB hard drive
Antec Sonata case that I already had

Got the parts and assembled the system. It uses 40 watts of power at the wall outlet when idle and it very quiet. I got a good CPU cooler and can run the system under load without the CPU fan at all. The cooler gets hot, but not too hot.

In order to install ESXi on to a Sata hard drive, you have to do a trick during install. This page outlines how to install ESXi to an IDE or SATA drive.
After install, ESXi came up and I accessed the management interface from a Windows computer. There is no management interface that will run from Linux unfortunately, as the program needs .Net to operate.
I proceeded to install FreeNas, XP and various flavors of Linux to play with. They all run excellently, and I use an XP VM and Remote Desktop installed on the ESXi server to run the management interface since I don't run Windows day to day on any of my home computers. They all have been switched to Ubuntu.
I have been running stable for a month or so now and am quite happy that I now and running my file server on a computer that I can use for other things now. Before, I had a freenas box setup and it just killed me that I couldn't really use that computer for anything else. Now I have 5 operating systems running on the same computer with room to grow and add more.

9 out of 10, and you can't beat the price.
Caviats: You wil want to use mainstream parts for your ESXi build. I couldn't get it to install and run on AMD processors or Intel Atom boards and processors. Admittedly, the Atom is wimpy for this job, but I had it already for use as my freenas system.
You will want to install ESXi on a computer with over 1 gig of RAM. running with just 1 gig doesn't give you much RAM available for Virtual Machines and ESXi will throw up an error if you add more than two VMs.
You can't ssh to ESXi in a supported fashion, however there is an unsupported workaround. Details.