Here's what I generally recommend:
1) rack mounted pc, with extensive filtering (if budget allows, otherwise, you can get creative with cabinetry, but remember shop time is $$$$)
2) fixed control pendant with basic controls, cycle start, pause, rewind, z inhibit (dry run), e-stop, feed rate overide, spindle,vac, and dust collector controls.
3) hand pendant connected to 2, with jogging and ref all (start here!)
controls.
this arrangement works best on larger machines for production type work, if you primarily do one offs, there are some advantages to having other controls on the hand pendant.
You've got to remember, we're not talking table top milling machine here,
we're talking big machines, my working area is 8'x12'. what works with a small machine doesn't always scale up easily. ( or safely!)
erie
www.shelbyvilledesign.com