Just for thought....a 5 hp compressor (not 5hp equivalent as Sears advertises) is a good starting point. Five horse motors draw someting like
22.5 amps at 120 vac......not exactly what your house wiring is designed for.

That's why any decent sized compressor is a minimum of 220VAC single phase.
Of course, your house doesnt have 460VAC OR 3 phase of any kind; both of which are more efficient.

mike in tucson