Reality Check for CNC mill

I'm looking to build a CNC mill and am currently in the design phase
and would like a reality check on my design. Any assistance or
opinions on my design choices you can provide would be great.

I did use MicroKinetics CNC Express as a sort of base idea.

Thanks

Base machine:
Enco or Rong Fu bench top mill converted to ball screw on the
X and Y axis.

Stepper package:
Stepper World FET-4 with the MOSFET upgrade. Uni-Polar Drive.

Stepper Motors:
X & Y axis NEMA 34's 344-610-DU 610oz 3.9v motors connected via
toothed belt at a 2:1 ratio.
Z axis NEMA 23 233-180-SU 180oz 2.7v motor connected via toothed
belt to the fine down-feed at a 2:1 ratio.
6 in Rotary table NEMA 34 344-304-SU 304oz 2.5v motors connected
via toothed belt at a 2:1 ratio.

Power Supply:
24v 60A unregulated. It's actually an old UPS and by
connecting across the positive and negative terminals I figure I
could get at least 60 amps plus a beautiful 3400-mAH reserve. I of
course clamp it with zeners for surge protection.

Current Limiting: (this is where I'm the weakest)
X & Y axis NEMA 34's 344-610-DU 610oz 3.9v motors will
be connected in series with 5 ohm 50 watt power resisters. (Not wire
wound)
Motor: .97 ohm
Power Resistor: 5 ohm
Circuit total: 5.97 ohm
Voltage 24v/ 5.97 ohm = 4.02 amps

Z-axis NEMA 23 233-180-SU 180oz 2.7v motors will be connected in
series with 5 ohm and a 2 ohm 50 watt power resisters. (Not wire
wound)
Motor: .9 ohm
Power Resistors: 7 ohm
Circuit total: 7.9 ohm
Voltage 24v/ 7.9 ohm = 3.03 amps

Rotary table NEMA 34 344-304-SU 304oz 2.5v motors will be
connected in series with 5 ohm 50 watt power resisters. (Not wire
wound)
Motor: .62 ohm
Power Resistors: 5 ohm
Circuit total: 5.62 ohm
Voltage 24v/ 5.62 ohm = 4.27 amps


CNC controller:
Pentium 400+ something running Win 2000 or Win XP
CNC controller software:
MACH 1 and upgrade to MACH 2 when available.
CAD/CAM:
BobCad v18 upgraded to v19 when available.