One way to mitigate the effect of computers is to use computers with power-factor-corrected power supplies. These pull very close to a pure sine wave from the building wiring.
Generally speaking, the power supplies that can take something like 120-240 volts in without changing a switch setting are power-factor corrected. (The power-factor-correction circuit has a side effect of allowing the "wide-mouth" input.)
I recognize that one typically has little or no influence on what computers are chosen, so this little tidbit of information is probably useful in only a few situations.
[This message has been edited by SolarPowered (edited 05-04-2006).]
