I always liked virtualization. It pushes breaking things to a totally different level.
I’ve been playing with ESXi at home for 3+ years, more or less since it was first released as a free version of ESX. Until version 5, if you wanted to deploy ESXi on (cheap) non-officially supported hardware, you had to rely on custom drivers built from the online community (vm-help is a great pool of answers), creating a custom tgz file which should then be injected in a file extracted from the installation ISO. Well, more or less.
All this was especially true if you did not want to go shopping for specific disk controllers and network cards. At some point, VmWare even took away support for the Atom processor family (it was probably a mistake, since the support came back in the next update).
Here enters ESXi 5.0, which finally adds out-of-the-box Realtek NICs (8168/8169) drivers, and supports all the hardware (at least, all the hardware you need to build a fully functional headless virtualization server) of the Asrock A330GC. Cheap, mini-itx, 1.6GHz dual core Atom CPU, one of the few Atom motherboards which supports ~4GB of RAM (just 3.5 available, sadly). Add a Pico-PSU, two sticks of 2GB DDR2 Kingston, add some storage (a 2.5″ sata hard disk is perfect), install ESXi on a USB key and you are ready to go with just a bit over 100$.
Even if the Atom isn’t exactly the speediest processor out there, for a home server works very well: four logical cores and 64bit are more than enough to virtualize a bunch of 32 bit machines (not VT-X, no 64bit guests), all in less than 30 watt/hour, passively cooled (if you remove the useless fan – as long as the enviroment is a bit ventilated), totally silent.
I’m not to say that there are no compromises, though: all the hardware sensors are not working (no temperature monitoring or similar), no VMDirectPath (hardware passthrough) and as I already said no 64 bit guest OSes, but if you really need these features, I suppose you can look at the HCL. :
Anyways, right now I have 7 VMs deployed, 5 of which (3 Windows XP, 2 linux) running 24/7 since 2009, and the only problems I had were human-caused (ok, me-caused, if you prefer ^^ ).