I don use a 600mhz cpu, but I cap my threads to 700mhz to avoid lockups. (I use a 1.3ghz SU4100 (c)ulv processor) and it uses around 30% wich is 30% of 700mhz. It peaks at 48 so its safe to say it should run pretty smooth on 600mhz. Also, 1024x768 bumps the framerate right down (glitch in prometheus_vid I'm working on).

So at this stage, thats where I'm at. Should be going ahead soon though.