Bought a cnc machine, need a lot of help

[paulus.v]

Hi Paul!

does the port have to be parallel or can use usb? which is best?

Given the CNC you are starting with and having old PCs laying around, I think you will be better and cheaper to start with a decent breakout board using the parallel port. The cheap USB controllers are not that reliable and a good USB or Ethernet controller will probably cost more than the CNC you bought.

I am assuming I can mount the drivers etc inside an old pc and use the pc's power to run everything?

If you do not want to spend money for a proper control box you could fit them in a PC tower case, I have done it myself.
As Doddy already said, depending on the drivers specs, you will need at least 40-50 V power supply for the NEMA23 steppers. To power the BoB, sensors, relays, etc. the PC PSU is fine.

Paul.