Belts or Balls getting me Screwed up! Help I need advice Please.

[JAZZCNC]

First you'll get a stronger machine if you build it long and narrow rather than wide and short. It would also be easier to join ballscrews with a timing belt and use one motor and have the advantage of keeping screws in sync. Don't bother with timing belts only as they cost nearly as much as ballscrews by time you have bought belt and pulleys etc.
Also the ballscrews want to be 10mm pitch not 5mm if you planning on mainly cutting wood, if you need higher resolution then just put a ratio on the screws.