@JAZZCNC: Thanks for the Great information and your time for posting.

I have started working on the Steel base Structure, I have the overall size but height will be adjusted/tweaked as soon as I get the machine completely drawn up.

Here is what I have so far, I am using 100mmx50mm Steel Box with 3mm wall, I am sure this will be more than strong enough.
Click image for larger version.  Name: CNC_Base_V2.JPG  Views: 676  Size: 82.4 KB  ID: 5476

Is there anything the looks glaringly/obviously wrong?

I will continue to work on the Design and keep everyone posted.

Use them on all Axis but with the Z axis mount the rails on the front plate and bearings on the rear plate, this will give the maximum strength when the Z axis is extended.
I am not quiet following you here, could you show me an example of what you are talking about?

Another option and something I like and know Jonathan likes to use is connecting the motors to the screws via a short timing belt.
Does anyone have any pics of a similar setup?

On another note regarding the Stepper/Ballscrew on both sides of the X-Axis, what happens when 1 stepper falls behind or fails?