arduino + winXP driver issue, always runs new hdwre wizzard

Im having an issue with Arduino uno and windows XP. every time a different board is plugged into the computer the driver must be installed. On another computer with vista I installed the driver once, and every time a different board is plugged in a com port is assigned without having to install driver.

linux is not an option. mac is not an option. windows upgrade is not an option. have to be able to use multiple arduinos on these winxp machines without going through the driver install process every time a different arduino is connected to the computer.

any thoughts?