How fast is too fast on a Bridgeport?

I'm tuning my NEMA 42 stepper motors with MACH2 and find that I can
make the table on my Bridgeport move at blindingly scary speeds (in
excess of 20 ips). I've slowed it down, but don't have a clue what
is an approprite speed and accelleration setting for the X, Y and Z
axis? I'm currently running 1000 steps per inch. The table also
seems to continue to move (from momentum, inertia) after I release my
manual jog button. Is this normal?

Thanks and regards,
Jeff