Jim, are you talking about the Windows power settings, or something in the Mach3 setup? You're right, it's a good idea to make sure your CNC controller is not set up as a notebook or for "minimal power management" or else it will try to save a few watts of power by lowering the CPU clock speed when it can, and that's not good for performance. I don't think that's causing Monte's terrible motor performance, however. It sounds like his machine won't even make a straight line. I just found a P4 2.5 Ghz computer in the garbage, by the way, so if CPU performance is the problem, the good news is that it's now the cheapest thing to upgrade.
Monte, if you want to use your oscilliscope to see what's going on, here's what you do. Take one channel and put the positive on Pin 1 of your parallel port, which is the step pin for your X axis. Put the negative on the ground pin. Put the positive of the second channel onto Pin 2, which shows your direction signal, and put channel 2's negative on the ground pin as well. I don't know your scope, but it probably has knobs for each channel for the time and voltage scales. Basically you want to zoom in on 5volts, and about 10,000 Hz. You can probably just turn the knobs until you see stuff. Don't worry, it's impossible to hurt an oscilloscope with a parallel port. Just turn off soft limits in Mach3 and (without the machine connected, of course) use "g0 x10000" to keep the signal coming while you watch. What you want to see is two wave forms like the one in the graph I posted from from the Xylotex manual. The reason they put it in the manual is because it's essential for the operation. I wouldn't bother with the scope until trying the values I suggested above, however, but it would be fun to change the pulse timings and see what it looks like. I'd love to see what it looks like.
Cheers,
Anthony