Stepper Motor Power?

[metricmike]

I just picked up a shop bot table without gantry, really good deal, but just the table and x axis (very good start to the project though). Im looking at purchasing my steppers, controllers, power supply, etc. and Im a little unsure what size steppers I need. I understand the different NEMA numbers (23, etc.) meaning their mounting pattern size, but im unsure about the "oz-in" rating I need.

A little about what I'm trying to accomplish:
I plan to have an x,y, and z axis. Going to use it for plasma cutting steel, as well as hooking a router up to it for milling aluminum. The table is 4' x 4'.

As well as the stepper question, Im wondering if I should be dual driving my x-axis. Will the torque of the router come in to play when thinking about motor power as well as dual driving it?

Is a setup like this any good?
3 axis Nema23 stepper motor 425oz-in CNC controller kit - eBay (item 300488126022 end time Dec-01-10 04:25:09 PST)

[Fastest1]

Well the 425oz steppers would get the job done. He has 100% positive feedback. Everything he sells is cnc related. I dont think any real strength is required for the plasma. The router might be a bit more of a load for the steppers but I think they would be able to push it fine. If it is a gangtry type router, dont they always slave a stepper so both sides of the gangtry are parallel? I know they run seperate limit switches on each side of the gangtry for squaring it up when reffing. Personally I would go with a Gecko, Keling or a Hobby CNC Pro kit. They are a little more but the support on all 3 are fantastic.