Ok, let me see if I understand. Maybe I can clear everything up.
You have a DDR machine, but you want to put a PC with Stepmania inside it. You want to play Stepmania on your DDR machine. You are afraid of damaging your monitor because the sync rates are different in your PC and your arcade monitor. You don't have an ArcadeVGA video card because they are expensive so you want to use Powerstrip.
Does that all sound correct?