Know how you feel man, had exactly the same probs with my via epia 800 tried everything
Hard drive, CD Rom, Memory, Cables, Power supply, including a new motherboard and windows xp home edition, also flashed the bios with latest version none of these cured the problem, eventually managed to Install xp with no copy file errors. persistance won the day in the end, lost count of how many times I ran setup to get to this stage.
Best of luck ShaunP