New Setup - Moving From Mach 3

Hey all,
It is time for me to more from Mach3 to a new system. I was thinking about going the Mach4 route and decided LinuxCNC is the way to go. Can you please suggest a good computer and machine controller combo? I am most likely going to be using an ethernet solution. I was hoping for some sort of all-in-one that could get the job done.

Thanks!

HP 8300 SFF and one of the Mesa cards, 7i92 or 7i96 or 7i76E or even the new ones like 7i95.

A whole setup for around $400, that is great, thank you @tommylight! Now going down the Mesa rabbithole...