microstepping torque

Hi all,

I've a question about microstepping. If I look at the speed vs.
torque diagram, the steppers I'm using have a torque of 3 Nm (460
0z/in) at 5000 Hz. This in half step mode, if use microsteppers what
happens with the torque.
With microsteppers I use 5 times more steps for the same revolution,
so at 5000hz the microsteppersriver is sending 25.000 steps. The
torque at 25.000 Hz is pretty low.
So basicly the questions is how does microstepping inflect the torque?
Thanks

Hugo