Set your timezone to GMT (UTC). You can use sudo dpkg-reconfigure tzdata to pick the right timezone.
Keep your time as accurate as possible: Install the "ntp" package. I believe the defaults are good on Ubuntu 10, but you may want to edit /etc/ntp.conf and add a few lines like server 0.us.pool.ntp.org and server 1.us.pool.ntp.org; you'll want 4 or more of those. You'll have to restart the ntp service for those changes to take affect.