The installer might ask you if the computer's clock is set to UTC. Normally this question is avoided if possible and the installer tries to work out whether the clock is set to UTC based on things like what other operating systems are installed. In expert mode you will always be able to choose whether or not the clock is set to UTC. Macintosh hardware clocks are normally set to local time. If you want to dual-boot, select local time instead of GMT. Systems that (also) run Dos or Windows are normally set to local time. If you want to dual-boot, select local time instead of GMT. Note that the installer does not currently allow you to actually set the time in the computer's clock. You can set the clock to the current time after you have installed, if it is incorrect or if it was previously not set to UTC.