BXBX,
My pc has other programs on it that i use other than Mach and all runs fine. The programs don't interfere with Mach, but, I know that from using similar setups over time. There is no anti virus on the pc and never goes out to the internet etc. So it is restricted in manny ways.
These days the computer is not the major cost factor in cnc.........my opinion. A dedicated PC is recommended by most CNC doctors.
Like going to a doctor, you get a script for the illness ,but, if the medicine is not taken properly,chances are your not going to get well.
Then again if you don't like the doctors advice, you always have option to use another one.......
Just an opinion as I don't have a license to practice.......
RICH