Running pfsense http://www.pfsense.org/
2.1 is current development release in a virtual machine
built on Fri Jul 27 15:20:57 EDT 2012
VM - virtual machine. http://en.wikipedia....Virtual_machine
N40L - is a HP microsever, http://www.newegg.co...N82E16859107052
Got it lot cheaper than that current price. Updated its 2GB of ram it came with to 8GB, and also added a 2nd nic (it only has one built in). This was so could use router on VM, one interface connected to modem, second interface connected to my lan. This is done via virtual switches that you assign physical nics too.
Vsphere 5 - just then new name for ESXI, 5 is the current version - running 5.0.0 u1 (build 768111)
This allows me to take snapshots of my router before upgrade - easy rollback if something goes wrong, switch routers to something else on the fly, say different build of pfsense, or ipcop, m0n0wall, smoothwall, generic linux as router, etc. etc. Many Many advantages of running your router in VM.
Also allows me to reduce power consumption, less hardware - just one tiny box (n40l) and run my router and all my other VMs without having to have multiple boxes. Other VMs on the box act as my NAS, my linux shells, my test workstation OSes, Test Server OSes, etc. etc.
Hope that helps clear it up.