New to CNC.

[JAZZCNC]

What are peoples thoughts on Mach3 or Mach4. I have a UC100 interface and it seems as if the difference at cost is $25.

If you have the UC100 it's a no-brainer to use UCCNC it's so much better than mach3, it's much more reliable and stable, the action is smoother and better still it's still supported and getting better. Mach3 is no longer supported and Mach4 is full of bugs and best avoided at all cost's. Also, UCNC is much cheaper than mach3 or 4.
I have used mach3 for nearly 20yrs and know it inside out and I can tell you with 100% confidence that UCCNC is the way to go.

Jazzcnc: With regards to the speeds, Yep your right, I did think bigger is better because of the length of the bed at 1800mm and was concerned about torque etc.
Nema 34, 8.7mn stepper driven by a cw8060 (6.0A 80v) Being supplied by a 480W 48V 10A PSU. 200 steps stepper motor and dip switches set at 1/10th.

It jogs along nicely but I was concerned about not over stressing the the whole system. I didn't want to drive it apart being over zealous.

Yes as expected and it's a common mistake for new builders to make. However, you do have spare room on the drives to up the volts and I recommend you do, I'd run them at 70V. You will see a marked difference in performance and power.