I saw that years ago. It's a "windows annoyance" that you dance around or get better software that can get the unadjusted GMT date/time stamp.
in other words, yup. XP does that but more specifically your backup app needs to know this about XP!
When my computer automatically changs to/from daylight-savings times
its causes my file's date stamps to change 1 hour (it keeps the same day).
I mean, files that were created years ago, change by 1 hour. This causes my
incremental backup to try to backup all my files.