Look on the back of the power supply on the computer. Somewhere close to the power lead socket there may be a switch marked "230/115" or "220/110", or similar. If so, move it to the lower voltage setting. If there is no such switch, DON'T DO IT!!.
It is highly unlikely that your scanner or printer or any other peripherals will auto-sense the input voltage. If they have a switch to set the voltage, OK, do it. If not, DON'T DO IT.
You can get transformers to change the voltage in the US relatively cheaply. Certainly a lot less cheaply than having to buy a complete new system because you've blown your old one up. I cannot stress this enough - if you connect the wrong voltage to your system, it will not work and will probably be irreparably damaged.