HI, can anyone advice me what´s the appropriate power in Watts or VAC of the step-up/down converter I need to buy to convert from my power source that is AC 220V 50 Hz to the AC 110V 60 Hz that PC 7424XP needs? I can buy locally the step-up/down converter but I need to know how many Watts or VAC the converter needs to carry so 7424XP works OK. Thanks in advance!