Which hosting application? Probably Oracle's Virtualbox. It's free, it's stupidly easy to set up (just remember to match the extensions package to the hot build version) and with hard drives so cheap it's economical vs. a bunch of hardware running a single OS.
BTW: I do run VM's on an external drive. It makes them fairly portable.
Thanks, that’s what I figured. I played with VMWare at one time but I think it’s no longer free.