linux & newer PC,s for BDI soft ware

I,m putting a engraver together & want to try Linux & the BDI
program. My questions are: Is anyone used this? How do you like the
software? What flavor of linux are used with machine control(is one
brand better for machine control than others)?
I purchased Red Hat, min install is 500 mb, max is over 2.5 gig.
Seems large!
Can anyone tell me what low level formating soft ware is used to
erase windows(95 & up) from old hard drives so older dos command.com
can be loaded allowing linux to be installed only as main operating
system? I have some older PC's I can dedicate to the engraver, but
need to get around the installed windows. Reformating can only be
done with the same or later version of windows. This leaves win 95
command com on the PC,cant get linux to recognise this as dos?
Thanks in advance
Dennis Cumin