microstepping speed?

Hi,
I am direct driving a slide with a stepper so as to return the cutter
to the home position after the cut as fast as possible, this makes
the
cut rather "ratchety" and less precise than I would like but I am
only
machining wood.
I have been looking with a great deal of interest at the Geckodrives
and their microstepping features (my controller only half steps) and
I
have some questions.
I have been lead to believe that the speed of the computer controls
the maximum speed a stepper can reach? So if I used microstepping the
stepper will run slower unless I upgrade my computer because more
pulses are required? I use a dos g code interpreter and an old 386!
Thanks, Terry Ackland