Opinions on CAD software

Does anyone have any opinions on what is the best CAD software for a
CNC milling machine? I am building a 3 axis gantry type machine driven
by steppers. The motors will be controlled by Pic List "Linistepper"
drive boards.

I intend to be milling PCBs as well as nonferrous metals & plastics.
Both the metals & plastics I expect to be fairly complex 3 dimensional
shapes.

I will be using a pentium based PC running XP. Cost is an issue, but
getting a good package is more important than outright cost.

Your advice would be most appreciated.

Tony.