steppers+feedback+emc

after milling some mdf with a stepper controlled table I think i need
to add feedback(encoders) to eliminate missed steps...

my question is:

would it be possible to hook up the encoders directly to the pc and
let EMC read them and act accordingly, ie. implement a PID controller
in (real-time) software ?
the parallell port pins won't be enough(?), but what other options
are available ? (serial?)

also, a question for EMC users: how does PC speed affect the speed at
wich you can do interpolated(linear, cubic etc.) runs on a mill?

thanx for any answers.