If all you care about is your windows clocking showing the right time then no worries. However, anything relying on timing will be effected (to some degree.) Like, if you set something to happen 36 hours from now, and so the schederal might get mixed up. Say you use outlook/exchange, and the date is set for one of the effect days. Since the date is stored in utc, (I think, but it doesn't matter, some kinda converson has to happen however it's stored, ) your outlook will convert the date to local time, but get it wrong. Anything that uses time will be effect, your system logger, any sqls your running, etc...