linux compared to centroid and acromill

that's awesome. Guess I need to get the computer built. I have a local shop here that will probably be doing that. Might even be a used one. If anyone has suggestions in addition to the wiki page let me know. thanks

That's the disadvantage of LinuxCNC; it doesn't need a fast computer, but one that can do things at a very regular interval. This is not something that is high on the priority list of most PC manufacturers.
I have good experience with the Intel Atom D525MW mainboard and the Asus Z77P8+Celeron G550. But pick a comparable configuration and it might be worthless.

With Mesa hardware this is already less of a problem than with software stepping using a parallel port, BTW.

You can run the latency test from the Live-CD. Maybe the guys at the computer shop are kind enough to boot the CD and run the test for a couple of hours?