DST happens on November 2nd in parts of the United States (Not Hawaii or non-Navajo-Nation Arizona) and Canada - which has changed from , which is different from when it used to occur prior to 2007. You'll need to set your clocks back 1 hour at 2 AM (or when you get up) on November 2nd this year. Computers should handle the DST change fine as long as the operating system and in some cases Java has been updated.
Still, I'll be checking my HTPC computers Sunday morning just to be sure it's showing the right time.
SageTV forum thread about the Fall 2008 DST change
Microsoft Update for MS OS's to update for the DST change (many already have this installed)