Problem with my computer's time settings?

I had to PC restore my computer (wipe it back to factory-fresh setting) because of a bad rootkit/virus problem about a week ago. My comp is working fine now, but the time is skewered, it says it's 6 AM when it's really 7, etc. I think it's a daylight savings/standard time problem the computer isn't catching, but whenever I change the time back it doesn't save. I'll turn off and turn on the comp and the time will be wrong again. It isn't a big deal but it's messing up my gmail time too, any help?