Controller for Servo Motor - Automation Direct

I have converted to CNC a Hardinge lathe by installing stepper motors on two slides.
The two sure step stepper motors of 234 oz inch, drivers and power supply are from Automation Direct.
The controller card C1G Rev.4 from CNC4PC.
Mach 3 is running the CNC.
The spindle is driven by 1HP AC induction motor.

Now I would like to replace the 1HP Induction Motor with 1KW Servo Motor with its driver from Automation Direct.

I need your suggestions for going about the conversion.

1. For running the servo motor and Driver from a PC with Mach 3 what interface/ Card is to be used?
2. Can I integrate this 1KW servo motor with the existing set up, that is, mix steppers and servo?
3. Should I install a new card for servo motor and how it has to be connected?

Thanks,

R. Rossey

If you Want a good CNC
you should always go for PLC's
you can also see many options available for PWM based spindle Control.
PULSE WIDTH MODULATION this sends signals to the VFD Inverter which further Drives The Spindle.
Well for the Servo Driven Spindle I dont have much knowledge.

Thanks for the suggestion
I will study the PWM based spindle control
Is it accurate for threading and indexing