Better yet, for testing you can set it up in a virtual server.
Note that all "installers" for Vicidial (Vicibox.com for instance) will wipe the computer clean (repartition the HD ...) so you don't want to do this on a HD you're actually using for something.
That being said: both Virtualbox and VMWare are tested and function well for a single agent/development box. Don't try to use it in production for more than a single call, but for development that's all you need anyway. Certainly "proof of concept" to demonstrate to "boss" or "partners" that the technology works. And you can port your development configuration directly into a production server upon completion if you want to.
Any hardware will do. I've run it on a PII (not recently, mind you ... but we retired our last PIII about three years ago ... still running an old Celeron, though!).
If you have an old agent workstation without a monitor, excellent. You'll only need the monitor during buildout anyway. And that could actually be used in production for a few agents. But the best "tester/development box" is virtual. The reset button is a marvelous thing.
The demo CD is nice as well (just don't try to install from it, it's meant to be booted from not installed from!).