Thanks for replies;
Boyan: im hoping I wont have to worry about the inertia in the shaft, because, unlike a ballscrew I can place inline shaft support bearings to reduce the whip?

After shopping around, Zapp doesnt seem overly expensive when taking into account they do free postage at that type of money, and you do get good service and can ask stupid questions.

My linear rails have arrived (SBR25 for X) SBR20 for Y, and SBR16 for Z (please dont wince, for my application they will be fine)
im half way through building the frame (il apply pictures of the frame once done)

Before, I order the Racks, Im hoping to harness some brain power from you guys

Although this isnt going to be a commercial machine, I hope to make it well enough for it to be used a lot, and on a wide variety of thickness material, in order to achieve this, based on my limited research the maximum cutting speed I think i need to achieve is 6000mm a minute

Im hoping to get away with stepper motors (only because I have them and some 70v drives), and a old computer with parrelel port

(but servos and ess are not out of the question) I know how good they are from other machines...

MOD1 rack seems cheapest, assume I use a 22 tooth pinion, driven from, lets say a 200 input belt off a 100 tooth drive off a stepper motor. so essentially per stepper rev, Im achieving 44mm actual movement

i shall illustrate this as follows

a) 22/200/100 = 22 1:2 == 44mm
b) 22/100/400 = 22 1:4 == 88mm

assuming I have the servo drives set at 400 pulses per rev, my parrelel port will need to kick out 6000 / 44 = 136 * 400 (54,400) PULSES PER MINUTE which I think is achieveable from a < 1khz parrelel port kernal?

but im tired, so can somebody shed some light?