VMware is generally used in large corporates and is more powerful than XEN.

Okay, so it's been a while since I posted this, glad to see everyone's opinions. I've started using ESXi a bit more, to see what it's got to offer.

The HA/DRS point is a good one, and that's my next point to experiment with as right now, I tend to just use OpenBSD with it's 'carp' feature offering HA, but if there it a better way to do this, them i'm certainly interested :D

Does anyone know of any software that allows multiple ESXi machines to be connected too at the same time, instead of needing the application open a different time for each physical server?! :confused: