I'm unclear what you're talking about here. From Apple's own web site:
iMac G5:
Electrical and environmental requirements
* Meets ENERGY STAR requirements
* Line voltage: 100-120V AC or 100-240V AC, depending on country of purchase
* Frequency: 47Hz to 63Hz, single phase
* Maximum continuous power: 180W
* Operating temperature: 50° to 95° F (10° to 35° C)
* Storage temperature: -40° to 185° F (-40° to 85° C)
* Relative humidity: 5% to 95% noncondensing
* Maximum altitude: 10,000 feet
They do make a dual voltage version of the iMac G5 and, as listed above, the iMac Mini. I can't say for sure whether the US version is the 100-120V or the 100-240V version, but you have the option of purchasing either. Whether you do it in the States or in Europe is a matter of preference and currency.
Timothy
I will check in the next US Apple store I visit, though. Just to solve the mystery.