You’ll need a transformer to step up the voltage for devices that can’t operate at 110V.

Sean’s note: Good news — most desktop computers these days have a switch on the back of the power supply that allows them to be easily switched between 120 and 240 volts…all you’ll need to do is buy a new power cord from a local PC shop, flip the switch to the right setting and you’re back in business. As for any portable gadgets with power bricks, they typically convert voltage automatically in a range that covers both countries. Again, the only thing you’ll need to do is to ensure that you have the right prongs…there are products available from companies like Kensington that will allow you to plug in your old gadgets and change the prong style to the North American standard, and the transformer in the power brick will automatically convert for you. If you don’t want to buy a truckload of adapters, you might also want to check with the manufacturers of your gear…they may also make the North American adapter available for less than it’ll cost simply to replace the whole gadget.

Very important though: do NOT plug in any ELECTRICAL devices that don’t have a voltage selector (computer, hair dryer, etc)…you can use the adapter to change the prong type but if the voltage is wrong, you can seriously damage your devices.