My work windows computer was syncing to a domain server which has it's time wrong by about 2 minutes. It was annoying me because I was ending up slightly late to meetings etc. If you want to change your computer to sync to different time servers, open up an administrator command prompt try the following:

w32tm /config /update /manualpeerlist:0.pool.ntp.org,1.pool.ntp.org,2.pool.ntp.org,3.pool.ntp.org /syncfromflags:MANUAL
w32tm /resync

After a few minutes hopefully your clock will be closer to the real time: http://tycho.usno.navy.mil/cgi-bin/timer.pl